Thursday, January 04, 2007

Computers, bloody computers: Firefox and js3250.dll

Next to "Cathy Baker", the search term mentioned in the previous post, the biggest source of Google search hits for my site has been "js3250.dll". This little file has been the source of many Firefox problems for me in the past. Whenever Firefox refuses to open, js3250.dll is indicated as the responsible party. (I don't know if this is related to my current Firefox problems in which Firefox simply freezes up in the middle of a session. I'm now using Firefox only to check the RSS feeds coming from my friends' sites for new posts - which I will then open in Internet Explorer.)

Unfortunately I don't have much to offer on this, except a series of posts complaining about the lack of official Firefox information on this problem, and metaposts like this one. This problem is nebulous enough that it doesn't warrant its own label, and is just lumped under the "Computers bloody computers" label.

You would think with this many people being affected by a single problem, someone at Mozilla would look up and say "Hey, we should do something about this." But I guess they're just waiting for the open-source community to figure out a solution on their own.

If anyone does have anything more solid to offer than what I have posted on this blog, please leave a comment a fill the rest of us in. Thanks!

From the Mozillazine forums:

Kabli Posted: Dec Sat 9th 2006 5:19pm
This is usually is a malware that is deleting the js3250 file.
"Go to C:\Windows\System32\ipv6monl.dll and delete it. Reinstall Firefox and it will work fine."

If it was there you should do a full scan to see if there is other remaining malware. I use ewido (now by avg)

timothylee Posted: Dec Sat 9th 2006 9:35pm
dickvl: yes, the actualy file is deleted

Kabli- THANKS! it works fine now!

khanjrx Posted: Jan Wed 3rd 2007 8:37pm
Kabli wrote:
This is usually is a malware that is deleting the js3250 file.
"Go to C:\Windows\System32\ipv6monl.dll and delete it. Reinstall Firefox and it will work fine."

If it was there you should do a full scan to see if there is other remaining malware. I use ewido (now by avg)
Hi. I'm new here and I just have a question.

In relation to the malware file mentioned above, I found one on my computer that has a similar file name: "ipv6mon.dll". Although mine's missing that extra "l", is it considered to be malware also? Because I know it's possible that it might be different for everyone.

Guest Posted: Jan Wed 3rd 2007 8:53pm
There is a legit file that is ipv6mon.dll . Malware often does this, that is, using a name that is similar to a real one.

So. Maybe this is the answer to the js3250.dll problem that is frustrating Firefox users everywhere? Let's hope so!

UPDATE, 7/2/2008: Judging by my recent traffic, it looks like the recent release of Firefox 3 has not corrected this problem. Mozilla, what are you waiting for? Some user to solve this problem for you? Oh, wait, that's right...

UPDATE, 8/2/2008: Check out this (unfortunately anonymous) comment from this post:

Hi... I starting having Firefox constantly saying it had to close - the culprit being js3250.dll. After trying the different methods here and quite a few other sites too and being unsuccessful fixing the crashes, I figured it was Javascript related - so I uninstalled all 4(!) versions of Java(TM) 6 Update 4,5,6, and 7... then reinstalled just Java(TM) 6 Update 7... and voila!... Firefox now working like a dream!... cheers :)

...and this follow-up:
Hi again... Oops, forgot to mention I then uninstalled Firefox via Ad and Remove programs, then reinstalled same Ffox version... and I didn't even have to reload all my addons, bookmarks, etc, etc with Feebe, as I thought I would have to... phew :)


Anonymous said...

I am having this same problem, and so far no solution. I've run scans by Panda and Ewido, but they shutdown and close Internet Explorer halfway through. It could also be because I'm simultaneously surfing the Internet. I'll try again without surfing the Internet and update IE...

Anonymous said...

and also, I tried a PC clean up tool, and it gave the same js error message after the scan when I tried to fix errors. all of this happened after running ad-aware. spybot also produced errors after i ran it.

Anonymous said...

omg! This distant blog has shown me up to be a fool. Have had this stupid issue for ages and BANG I find a trojan after a scan all because of THIS blog.

A thousand thank-you's from an I.T. guy who thinks his laptop is invulnerable ... and of course is wrong!

My file was ipv6monl.dll (a minor variation which is common in the malware field) and in additional I found a trojan file dropper. All clean now!

Anonymous said...

I have both
C:\Windows\System32\ipv6monl.dll and
and you only need to delete the first one.

Anonymous said...

Hi! i also have this problem...
but i don't have the files


and firefox shuts down only if i want to open a folder too...

if anyone finds another answer let me know... at


Anonymous said...

Did you find the solution? I also don't have ipv6monl.dll. And i've skanned my computer for viruses with the latest virus database. But the problem still there.

D.B. Echo said...

I haven't had this problem since I took the actions described in this post, but I wouldn't be suprised if there are more Firefox-specific trojans and viruses being written all the time. I think your best chance for a solution is to cruise the Mozillazine forums ( and other Firefox users groups, until Mozilla decides to formally start providing support for its products.

Anonymous said...

i'm having the same problem - but again, like previously mentioned - i have only the legit ipv6mon.dll and not the malware ipv6monl.dll.

This is ad too, because I've tried other browsers such as opera, maxthon, safari - and they too crash - just not as often as firefox.

I really like my firefox other than the fact that it crashes twice every hour practically.

Oh, and I have also been on the Mozilla forums and tried creating a new profile. No avail.

MathEWW[3][16] said...

I am currently working in Internet Explorer as we speak, solving this issue. I too found the ipv6monl.dll. This computer was infected with multiple trojans and other annoying spyware/malware. My fiance's aunt isn't too tech savvy so she doesn't have an antivirus of any kind (until now).
The steps I took are as follows:
- Start up your computer in Safe Mode with Networking.
- Log in under the Administrator account.
- Go to the antivirus website of your choice and download the AV installer .exe
- Make sure to save the file in C:\ or somewhere accessible by all accounts.
- Right click the file, check the "Read Only" option, just in case you have a virus that will try and infect the new .exe upon bootup when not in safe mode. The reason you cannot proceed in safe mode is because the drivers and services required to run AVG and I assume virtually any AV program aren't allowed in safe mode.
- Reboot your PC in normal mode and navigate back to wherever you saved the installer file.
- Run the installer, go through all the set up and configuration steps, and update the virus definitions.
- After everything is up-to-date, run a full system scan with high priority if that is an option for your particular AV.
- I used AVG and it automatically cleans files after the scan is complete. Reboot your computer and reinstall Firefox.

Another thing that was extremely useful to me in this entire process is the file WinsockFix.exe by Option^Explicit Software Solutions. I didn't need it specifically for the Firefox problem, but the malware had also crippled any and all winsock activity. I actually recommend saving it to a disc so that you don't have to find another computer that has working internet to download your files, but that's just my opinion.

Anonymous said...

I have the same problem after a clean install of xp/sp2. Installed version of firefox after all the M$ updates. Tried the possible solutions @, to no avail. It still crashes w/same js3250.dll error even in safe mode. The system is malware/trojan free. Strange thing is that my 3 other xp pc's with firefox & other similiar software, run fine.

Anonymous said...

An update to my comment posted 10/19/07 - It appears the buggy js3250.dll that affected some is cured with firefox 1.8.18

D.B. Echo said...

Excellent! Though I have a feeling we haven't seen the last of this.

Anonymous said...

Nope, I'm on and still get the js3250.dll crash; I've been getting this since

Anonymous said...

Its due to bad ram chip(s). Test your modules using memtest86 :)

Anonymous said...

Bad RAM chips produce overall system crashes... like BSOD's.
So bad RAM is out of the question!

I haven't found any infections so far... and I've scanned my system wit about 5 of the bet anti-mall ware software and 2 AV's!

So the Trojan solution is limited to a few ppl... sorry but I have to call them n00bs, that didn't/don't have an AV installed!

The problem persists!

Anonymous said...

I started having this problem this past week and reinstalling firefox would only solve the problem temporarily. Something was deleting the js3250.dll. I finally traced the problem to windows explorer - I had firefox open and I went to open explorer (e.g. - "My Computer", etc.) and firefox crashed - it was the act of opening explorer that caused the necessary dlls to disappear. I then found two dlls that had appeared on my computer within the last week. I quarantined them both and voila, the problem disappeared. I then narrowed it down to just one of the dlls - "mskvtns.dll". I haven't been able to find any information about it on the web and a file scan shows it to be clean, but since I moved it out of the windows\system32 directory, I have not had the problem anymore.

D.B. Echo said...

Cool. That's major news!

Anonymous said...

Just an FYI ~ I'm running and I still get this crash. I'll look at mskvtns.dll too and see what comes up.

Anonymous said...

I put the js3250.dll from my Thunderbird and thus far, it hasn't crashed on me yet...

I've been getting all sorts of stupid crashes ever since came out...

Polline said...

I'm still having the same problem with this js3250.dll file. I do not have the ipv3monl.dll file (well I can't find it, if I do) and I have tried 2 AV and malaware. I still don't have any success. I'm currently trying the msktns.dll file. I d/l a new FireFox and everything seems to be maybe that was the answer! Thanks

Natasha said...

I am still suffering my problem consists of, if I have Firefox open and I double click on something on my desktop or open Windows Explorer, then Firefox closes it self when I try and reopen it it says it's missing: js3250.dll I'll reinstall and everything workd fine untill I click on WE again!
I don't have either of the .dll's mentioned so I can't very well delete them, anyone have any ideas?

Polline said...

I had the same problem that I couldn't find the ipvmonl.dll file but once I deleted the msktns.dll file, there were no more problems! You can find it under C://windows/system32. Hopefully this helps you.

Bob Coughlin said...

As a previous user stated, removing or renaming the file "mskvtns.dll" fixed the error. I happened to find another file, modified at the same time as the previous file called "msdtexch.dll" and I renamed that one as well.

It may be a variation of the same malware users reported as "ipv6monl." In order to narrow it down properly, I recommend using the same method the previous user and I did in order to find our problem files. We found the files by sorting by Modified in the system32 folder and looking for files modified recently, around the time symptoms may have began. If you're not sure about a file, google the .dll. Frankly there shouldn't be many recently modified system files anyway.

All the other ridiculous comments about RAM chips and hardware issues on other websites are bogus. Its too bad our scanners don't seem to pick up on some of these files but this method should work for you....

I have covered this on my blog as well, saying as how the solution on this site is in the comments rather than a dedicated post:

Best of luck to you all.

daryl said...

Hi all

i don't have any of the offending files- so cannot delete them is one of the pages that constantly crashes firefox when not in safe mode.

Just wondering if it is something to do with the googlesyndication script



daryl said...


have just disabled firebug and the link nolonger crashes firefox

wherezat46 said...

... dont have ANY of the malware dll's that everyone is saying to delete or move... and My firefox won't open, missing js32... yeah you know... anyone found a solution besides the bad dll's???

Rene said...

Jan 28, 2008
I have to throw a monkey wrench into this mix.
I am getting the js3250.dll pop-up error when trying to open an exe.
This is the error I get in Event Viewer: Event ID 26
Application popup: 89176.exe - Unable To Locate Component : This application has failed to start because js3250.dll was not found. Re-installing the application may fix this problem.

NOW, here is the monkey wrench.
I am having NO problems with Firefox at all!
I have the file C:\Windows\System32\ipv6mon.dll

So .. I guess it's time to really scan for bugs, and see if I can kill this problem.


Anonymous said...

I had the same trouble (crashes caused by js3250.dll).

Could also solve the problem by disabling Firebug!

Anonymous said...

I hard setting it as read only fixes it.


Anonymous said...

look here

blargh23 said...

I don't have either of the trojan files mentioned in the MozillaZine article.

Scans with Spybot S&D, AdAware, PreVX, and Kaspersky's online scan all come up clean.

blargh23 said...

Fixed it by making a new profile.

Moved my bookmarks to the new profile and deleted the old one.

Bobby said...

js3250.dll has been a major pain in the butt - but I think I've found the definitive fix for my situation.

I have several Win98 SE machines on a network, all with Firefox Firefox crashes often right after user tries to send a page to a printer - js3250.dll exception

Finally, after trying all of the suggestions on this page and others, I decided to try another gecko based browser. I downloaded K-Meleon ( & and installed it. It's a nice browser. No crashes. (might give it an extended try, but all users on my network know and love Firefox)

I copied js3250.dll from K-Meleon program folder to Firefox folder, then tried to start Firefox. It complained about a missing msvcr71.dll and wouldn't start, so I grabbed that dll from K-Meleon folder and copied it to Firefox folder.

Now Firefox starts and prints pages just fine. No crashes.

Summary: grabbed js3250.dll and msvcr71.dll from latest stable build of K-Meleon and put them in Firefox program folder

I don't know if the dlls from K-Meleon will have any bad effects on Firefox, but so far it's all good.

Anonymous said...

i just downloaded the new version of firefox and it worked

everythings still bookmarked and all.

Anonymous said...

Try keeping a "working" and "read only" copy of js3250.dll [mine is version] in a "3250" subdir "close to" Firefox and simply copy it over when the problem arises. In my experience, the problem has always been due to a FF "update" that also includes an "updated" js3250.dll. Since I've begun using FF mobile [for several years], this has never failed to fix the problem. I've not found any other attendant problems, malware, etc, after any of these copies.

Anonymous said...

if the previous poster meant ForceField... then yes, that has been my experience... if I try to start Firefox with FF running, it gives me the js3250 error... if I close FF then start Firefox, it works! not sure how to correct FF? I don't want to keep opening and closing FF if I don't need to...

mazinoz said...

After disabling Force Field browser security in ZoneAlarm Extreme Security, I could open Firefox 3.6, but not IE8. Re-enabled FF and Firefox gave error message about js3250.dll ..GetPropertyby ID..FakeFrame etc.

I could use Google Chrome ok but not the other two browsers with FField.

Mark Ribbans said...

Hi there,

It's now late 2010 and I've jsut installed an update to Thunbderbird (3.1.5) and now it won't load. I get the error: C:\ProgramData\Mozilla Thunderbird\js3250.ddll is either not designed to run on Windows or contains an error. Try reinstalling the program etc...

I can't find any references to this particular error, so thought I'd post something here..