Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

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

I figured out that a few of the crashes succeeded in uploading their dumps. The reason for crashing is running out of memory. Even under 64-bit Windows with more than 4GB of RAM and many GB of pagefiles available, Firefox runs in a 32-bit process with limited virtual address space.

I have around 50 tabs open to ordinary information sites. At home I have a tab open to Youtube playing music, but at work I don't. I don't know how these tabs use more than 1.5GB of virtual RAM. But they do, and Firefox gets confused.

I read that Bugzilla already has OOM (out of memory) marked as a big reason for crashes, and Mozilla's volunteers marked it as WONTFIX.

I understand that Mozilla's volunteers are volunteers and I can't complain about WONTFIX. But the attitude is equally offensive as Microsoft, blaming users when the maker's bugs are the maker's bugs.

Java Script is mentioned in the crash report.

Hello,

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that turns off some settings, disables most add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• In Firefox 29.0 and above, click the menu button , click Help and select Restart with Add-ons Disabled.
• In previous Firefox versions, click on the Firefox button at the top left of the Firefox window and click on Help (or click on Help in the Menu bar, if you don't have a Firefox button) then click on Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

I clicked the menu button, clicked the help button, and clicked to restart Firefox with Add-ons Disabled. The Firefox Safe Mode dialog came up. I clicked the button to Start in Safe Mode.

Strangely, web sites that depend on JavaScript (such as Yahoo e-mail) were working properly.

I clicked on the Help menu - Firefox Health Report. It says 1 Add-on is enabled and 0 Add-ons are disabled.

This is safe mode?

The Add-ons Manager (about:addons), left-hand tab for Extensions, says "! All add-ons have been disabled by safe mode." Troubleshooter 1.1a is disabled. There are clickable buttons for Disable and Remove, but no button for Enable.

So which add-on is enabled? I don't know how to find it.

Appearance, Default 31.0, is also disabled. I wouldn't have guessed by looking at the Firefox windows; I only noticed when looking through the Add-ons Manager.

Windows Task Manager says that 4 processes are executing instances of FlashPlayerPlugin: C:\Windows\SysWOW64\Macromed\Flash\FlashPlayerPlugin_14_0_0_145.exe

Oh yeah, the Add-ons Manager tab for Plugins says that Flash will always execute instead of asking to execute.

So even in safe mode, Flash is enabled instead of asking?

I don't see any mention of JavaScript in the Add-ons Manager. An unrelated plugin named Java was updated from U65 to U67, but that one isn't even running since it's set to Ask to Activate and I haven't been asked. I don't know how to find if a JavaScript extension exists and is enabled when it's not supposed to be.

Good news is that this setting seems to be helping, though I don't really understand it since Flash is active. After restarting in safe mode, Firefox has run for more than 3 hours of CPU time and has occupied more than 2,000,000 KB[*], and yet has not crashed.

I still don't know what's occupying most of that memory. At home I'm playing music on Youtube, which takes its share of CPU time, but apparently not much memory. At work I don't do that, but tabs displaying ordinary information still occupy nearly 2 GB and Firefox's crashes are probably due to out-of-memory.

[* I nominate the word "disunit" for memory occupancy shown by Windows Task Manager. 2 * 1024 * 1024 * 1024 would be 2GB in binary units, 2 * 1000 * 1000 * 1000 would be 2GB in decimal units, and 2 * 1000 * 1000 * 1024 is Microsoft's disunited combination.]

Firefox 31.0 crashed while running in safe mode too. Before crashing, it reported errors with two JavaScript scripts, so it looks like JavaScript runs in safe mode too, without asking.

Java, Flash and some others are in the add-ons manager under Plugins. Go there and Disable Everything as a test.

Java was not running. Firefox 31.0, running in safe mode before crashing, reported errors with two JAVASCRIPT scripts, so it looks like JAVASCRIPT runs in safe mode too, without asking.

In the add-ons manager I see a setting for Firefox to ask before activating JAVA, which is set by default and I have not changed it. I have never been asked and I assume JAVA has not run at all.

In the add-ons manager I do not see any setting for JAVASCRIPT.

In the add-ons manager I see a setting for Firefox to run Flash without asking, which is set by default and I have not changed it. I understand your suggestion to change it. I have mixed feelings about whether to try it.

I think you're blaming Flash for a problem with Firefox's JavaScript.

If you can say how to disable JavaScript (both in safe mode and normal mode), I will try it.

In safe mode, only add-on extensions and user setting are disabled. Plugins are not unless you disable them.

https://support.mozilla.org/en-US/kb/javascript-settings-for-interactive-web-pages JavaScript settings and preferences for interactive web pages This article describes what JavaScript is and how to allow or block it on certain websites.

Please post your latest crash reports. Note: If the report does not have BP in front of the numbers, click it and select Submit.

You can try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

You need to close and restart Firefox after toggling this setting.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes
• https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder)
• default toolbar layout is used (localstore-safe.rdf file)
• JavaScript JIT compilers are disabled (about:config page: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)

• plugins are not affected
• preferences are not affected

I looked at page https://support.mozilla.org/en-US/kb/javascript-settings-for-interactive-web-pages

NoScript is described as an extension. All extensions are disabled when Firefox is running in safe mode, right?

The Plugins tab does not include JavaScript in the list.

Is there some way to disable JavaScript in Firefox? If there is a way, I will try it as an experiment.

I understand the suggestion to disable hardware acceleration in Firefox, but again it seems odd. When video drivers crash they ordinarily give BSODs, or more recently Windows 7 can restart a bug-ridden video driver instead of BSOD.

I think more likely the problem is in Firefox's implementation of JavaScript. As someone else pointed out, JavaScript is mentioned in the crash dumps, and there is a JavaScript bug listed in Bugzilla with status of WONTFIX.

---

"In Firefox Safe mode these changes are effective:

   all extensions are disabled (about:addons)"

Yes, I noticed that.

"JavaScript JIT compilers are disabled (about:config page: javascript.options.*jit)"

That does not seem to be true. I'm running in safe mode now. javascript.options.baselinejit;true That is the only jit option.

The prefs aren't modified if you enter safe mode as this disabling is done internally. You would only notice a difference on JavaScript intensive pages that benefit from using the compiler to speed up the execution.

"The prefs aren't modified if you enter safe mode as this disabling is done internally."

OK, BUT: Even when running in safe mode, Firefox gave 2 errors about JavaScript scripts before Firefox crashed. That means that Firefox was running JavaScript instead of disabling it, even in safe mode, right?

I manually toggled it in about:conf so it is now: javascript.options.baselinejit;false

I restarted Firefox in safe mode again. We'll see what happens.

Even in safe mode, the crash dump lists JavaScript: https://crash-stats.mozilla.com/report/index/f7777dab-e408-43a3-b00d-c6ac32140816

JavaScript runs normally in safe mode unless you would disable it by setting javascript.enabled = false on the about:config page. Only the JavaScript compilers are disabled that speed up the execution, so JavaScript runs slower.

OK, I changed this one: javascript.enabled;false

Now Yahoo Mail doesn't work.

I'll reenable JavaScript again.

I'll leave basejit disabled and we'll see if it helps.