Can you give us your last few Crash IDs? Instructions here: https://support.mozilla.org/en-US/kb/Firefox%20crashes#w_get-help-fixing-this-crash

Also it could be an issue with hardware acceleration. More info here: Latest Firefox issues

I can't give crash IDs, because crash reporter doesn't come up. about:crashes shows only crashes from months ago.

Don't know if it's related, but I previously had a similar problem (reported and unsolved at https://support.mozilla.org/en-US/questions/881543 ) which gave crash IDs. Firefox 8 and 9 worked ok.

Still happens with hardware acceleration disabled (actually as far as I can see, hardware acceleration is disabled anyway because the (latest) drivers are blacklisted).

Any other ideas?

Try creating a new Firefox profile and see if the issue reoccurs. Instructions here: Profile Manager - Create, remove or switch Firefox profiles

Thanks. I should have mentioned that I'd already tried a clean profile, and it still happens.

If you have submitted Breakpad crash reports then post the IDs of one or more Breakpad crash reports (bp-xxxxxxxx-xxxxxxxxx-xxxx-xxxxxxxxxxxx). You can find the IDs of the submitted crash reports on the about:crashes page. You can open the about:crashes page via the location bar, like you open a website.

See:

• http://kb.mozillazine.org/Breakpad (Mozilla Crash Reporter)
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter
• https://developer.mozilla.org/en/How_to_get_a_stacktrace_for_a_bug_report

.....

Swarnava: Breakpad doesn't seem to be catching these crashes, as I said in the original post, so none of your reply is relevant.

If this is related to previous issues, then you can find some previous crash IDs at https://support.mozilla.org/en-US/questions/881543 (they didn't match anything known - I filed a bug, but others can't reproduce so it didn't go anywhere...)

you can try other Firefox version, i mean beta or Nightly

• firefox.com/beta

I tried the candidate build for the first 11 beta and the problem happens there also.

I might try aurora or nightly when I have some more time, but I'm not going to deploy those around the office anyway, so I think we'll just stick with 3.6 for now. Should be replacing our computers before 3.6 EOL in April, so hopefully the issue will go away then.

Have you tried deleting the Firefox program folder and reinstalling? Sometimes updates go bad and create "frankenbuilds". Delete and reinstall Firefox

Yes, completely deleted the Firefox program folder, and Mozilla folders in appdata (regular and local).

For the record, I've now also tried latest nightly and aurora and they both exhibit the problem.

It's hard to know what's going on when the usual diagnostics don't work. I can only give you comments about what has caused similar crashing in the past:

1) Malware or third party programs injecting into the Firefox process. If it's not malware, some security/sandboxing software can prevent Firefox from accessing vital files on the computer. --- You can try installing Firefox in a non-standard location or using the "Portable" version of Firefox which runs off a USB drive which can sometimes get around this kind of thing. 2) You mention having to log into Facebook ... is it possible that you have Facebook App that has buggy code and is causing a crash? Can you try with the same version of Firefox on a different computer? 3) Hardware failure (you mention it's an old machine) has sometimes manifested as a Firefox crash because something written to memory ends up corrupted. Nothing we can really do to help you, there.

Looking at your system info, it looks like you've used IETab? It's a very fragile plugin/extension (since it integrates IE and Firefox). I'm not sure how to disable it, though, but do give the portable version of Firefox a try.

Also better privacy looks to still be installed. Are you sure this is a clean profile?

1) I'm as sure as I can be that there's no malware. The only (resident) security software is MS Security Essentials, which is fairly simple and I don't think does any sandboxing or similar. There is, however, a whole load of other software on this computer, so I guess there could be something - don't think there's any easy way of finding out, and I'm not about to uninstall/reinstall everything. Portable Firefox crashes too.

2) Facebook isn't necessary to cause the crash, it just seems to be a particularly reliable way of doing it. Using just about any script-heavy site for a few seconds causes it. (Besides which, I've got apps disabled on my Facebook account...)

3) Subtle hardware issues I guess are possible, but it's odd that only certain versions of Firefox are affected by them.

I initially posted the about:support info from my usual profile rather than a clean profile. So, here's about:support from a clean profile:

 Application Basics

       Name
       Firefox

       Version
       10.0

       User Agent
       Mozilla/5.0 (Windows NT 5.1; rv:10.0) Gecko/20100101 Firefox/10.0

       Profile Directory

         Open Containing Folder

       Enabled Plugins

         about:plugins

       Build Configuration

         about:buildconfig

       Crash Reports

         about:crashes

       Memory Use

         about:memory

 Extensions

       Name

       Version

       Enabled

       ID

       Java Quick Starter
       1.0
       false
       jqs@sun.com

       Microsoft .NET Framework Assistant
       0.0.0
       false
       {20a82645-c095-46ed-80e3-08825760534b}

 Modified Preferences

     Name

     Value

       browser.places.importBookmarksHTML
       false

       browser.places.smartBookmarksVersion
       2

       browser.startup.homepage_override.buildID
       20120129021758

       browser.startup.homepage_override.mstone
       rv:10.0

       extensions.lastAppVersion
       10.0

       network.cookie.prefsMigrated
       true

       places.history.expiration.transient_current_max_pages
       25126

       privacy.sanitize.migrateFx3Prefs
       true

 Graphics

       Adapter Description
       ATI Radeon X300/X550/X1050 Series

       Vendor ID
       1002

       Device ID
       5b62

       Adapter RAM
       Unknown

       Adapter Drivers
       ati2dvag

       Driver Version
       8.593.100.0

       Driver Date
       2-10-2010

       Vendor ID (GPU #2)
       1002

       Device ID (GPU #2)
       5b72

       Adapter RAM (GPU #2)
       Unknown

       Adapter Drivers (GPU #2)
       Unknown

       Driver Version (GPU #2)
       8.593.100.0

       Driver Date (GPU #2)
       2-10-2010

       WebGL Renderer
       Blocked for your graphics driver version. Try updating your graphics driver to version 10.6 or newer.

       GPU Accelerated Windows
       0/1. Blocked for your graphics driver version. Try updating your graphics driver to version 10.6 or newer.

Having put Portable Firefox onto a USB drive, I tried other computers. Another computer with pretty much identical hardware and similar software crashes in the same way. Same USB Firefox installation (and of course profile) on a Windows 7 laptop and it works fine.

So, it's something in the hardware or software installed on these computers that some versions of Firefox don't like. I'm afraid diagnosing beyond that is more effort than it's worth, unless there's a quick way of doing it...

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
• http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Thanks - I've already used 4 of those scanners and 2 that you haven't mentioned. Seems really unlikely to me that it's the problem, but I guess there's no way to be sure.

Well the support info does mention a newer driver for your graphics. Wouldn't hurt to update and see if that makes any difference and at least you'd have a more recent driver installed.

Other than that maybe our security experts might have a trick for figuring out how to capture the crash.

I think the support info suggestion about the driver is generic - as far as I can find, the latest driver version that exists for the X300 is 10.2. They stopped releasing new drivers for it some time ago.