When you restart Firefox, a new .plist file will be generated.If the new preferences file is working well, you can trash the .plist file on the desktop.can cause Firefox to crash frequently or Firefox may crash at startup (bug 925459).Bit Guard is bundled with toolbars or other software; if installed, you will see Bit running in the Windows Task Manager.You may also wish to review the Firefox release notes for your Firefox version, to see if the issue and solution is listed under "Known Issues". If Firefox no longer crashes when you run in Firefox Safe Mode, go to the Add-ons Manager Extensions list, click the Disable button for every extension, and restart Firefox normally.
   Spector Pro for Windows computer monitoring software can cause Firefox to crash at startup or when opening a new tab.
If you use this product, try updating to the latest version or contact Spector Soft Support.
   PC Tools' Threat Fire anti-malware software can cause Firefox to crash at startup.
In addition to the products listed below, Firefox crashes can be caused by Internet content-filtering or parental control software such as Safe Eyes, Mc Afee Family Protection and similar products.
If disabling the software stops the crashes, contact the product's support site see if there are any program updates or settings you can change to work around the problem (or uninstall the program, if you don't need it).