You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

Sorry, I've already been that route and didn't find anything to help.

In order to be able to find the correct solution to your problem, we require some more non-personal information from you. Please do the following:

• Click the Firefox button at the top left, then click the Help menu and select Troubleshooting Information from the submenu. If you don't have a Firefox button, click the Help menu at the top and select Troubleshooting Information from the menu.

Now, a new tab containing your troubleshooting information should open.

• At the top of the page, you should see a button that says "Copy text to clipboard". Click it.
• Now, go back to your forum post and click inside the reply box. Press Ctrl+V to paste all the information you copied into the forum post.

If you need further information about the Troubleshooting information page, please read the article Use the Troubleshooting Information page to help fix Firefox issues.

Thanks in advance for your help!

I need to know your operating version, Firefox version and extensions if you can't get the troubleshooting information on to the forum.

• Have you a couple of recent crash IDs (like the string you posted before). since then ?
  If so please paste into your next reply
• Or has Firefox now stopped working entirely?
  1. if so try in Firefox's safe mode,e.g. by holding down the keyboard shift key as you start
     Diagnose Firefox issues using Troubleshoot Mode
  2. still not starting then try Firefox's safe mode from Windows safe mode
     http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-vista
• I note from the report you are using Fx 23.0.1 on Vista
• Running without AV software may increase your risks of picking up malware. It may be worth you scanning for malware. I append instructions for that.

Note it is always a good idea if malware is suspected to use multiple tools as they may pickup different things. Additionally as your current AV is expiring you may also wish to consider Microsoft's offerings as they may not be included by default in your OS but may be free of charge.

• http://windows.microsoft.com/en-gb/windows/security-essentials-download
  Protect your PC, Get Microsoft Security Essentials for the low, low price of free. Microsoft Security Essentials is supported on Windows 7, Windows Vista, and Windows XP.

Note crash IDs for submitted reports (they start with bp-) should be obtainable even if Firefox may not be opened by navigating in Windows Explorer to "%APPDATA%\Mozilla\Firefox\Crash Reports\submitted"

• see Troubleshoot Firefox crashes (closing or quitting unexpectedly)_get-help-fixing-this-crash If you can't open Firefox because it crashes at startup even in Safe Mode:

If you are not able to restart Firefox then as a stopgap measure and further troubleshooting step install and try this unofficial Firefox Portable

• http://portableapps.com/apps/internet/firefox_portable

For forum cross referencing purposes

• Report for your CrashID bp-8bc5e4c9-4f6c-4f34-a335-4e4cb2130908
  • Crash Signature: msvcr100.dll@0x10670

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner
• and adwcleaner (home site (French))

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Thank you all for your help! I had to post my questions and responses using Internet Explorer, as Firefox was completely inaccessible for a time. After restarting the computer, I found that I could open Firefox "As an Administrator". I finally ran an Adaware full scan one night, then a Windows Defender virus scan the following night. That seems to have helped Firefox: I can get on, now.

However, my computer is running very slow. I think I'll try one of the free programs listed above to do a further scan for anything the other programs might have missed.

Thanks for the advice! It's helpful to know how to access the error-strings.

Danielsgrl