There are a few features that are not disabled in Safe Mode: extensions, themes and hardware acceleration.

Even though acceleration is off? D2write and Layers - do not even show up in the crash report. It also looks like one of the rams are unknown, are your drivers up to date? Upgrade your graphics drivers to use hardware acceleration and WebGL

Please also try a http://www.memtest.org/ if it is not just one site.

You can try to disable hardware acceleration in Firefox.

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

You need 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

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

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 (prefs: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)

• plugins are not affected
• preferences are not affected

Cor-el:

Many thanks. I disabled Hardware Accel and that seems to have fixed it. The previous reply also guided me in the direction of the Graphics, so I need to discover why that is not right.

Thanks again PeterM

Spoke too soon. Disabling Hardware Accel. doesn't fix it. I tried searching for Intel 82853/82855 driver updates: Mozilla says update to version 6.1400.1000.5218 but Dell says the present 6.14.10.4363 is OK, so I don't know what to do. In any case the only sources of 6.1400.1000.5218 will only sell it!

Sometimes even Safe mode crashes and I have to try several times before it starts.

Any ideas?

Peter M

Cor-el:

In your reply you said..

"JavaScript JIT compilers are disabled (prefs: javascript.options.*jit) "

I cannot find how to enable/disable this - entering "prefs:..." to the address bar is not recognised.

I cannot see how to enable/disable "Default 30" in the Appearance AddOn.

Other than this, I have disabled all Plugins and Extensions and it still fails to start and leaves no crash report.

Peter M

You can inspect and modify prefs on the about:config page.

• http://kb.mozillazine.org/about:config

Thanks. I checked with Javascript disabled and it still fails to start, except in safe mode. I do see a brief flash on the screen when I try to start it. There is no crash report and nothing in Windows Event viewer.

In Tools|Addons|Appearance is shown "Default 30 (disabled)" but there is no "Enable" button. Is this relevant?

I know you don't like users to roll back to earlier versions, but would it help?

Peter M

Firefox/Tools > Add-ons > Appearance : Default (30.0) is the default theme in the current Firefox 30.0 release. So no need to worry about this.

You can try to create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

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

Cor-el:

Thank you for continuing to help me solve my problem.

I had already tried a new profile (didn't solve it) and run some extra virus checks (but not all of those you listed). Nothing found.

You did not answer my question "Should I try running an older version?" but I have now uninstalled v30 and gone back to v29.0.1 and that has CURED the problem.

I have changed Tools-options-advanced-update to "Check for updates but let me choose..." and I will stay with v29.0.1 but I would be grateful for your advice on what to do when there is another update (to v31?)

Regards Peter M