Firebug is an extension for extension authors to test with, in the hands of other people it is probably very unstable. The recommendation in Problematic Extensions is disable it when not using it. Also check your other extensions to the list.

• Problematic extensions - MozillaZine Knowledge Base
  http://kb.mozillazine.org/Problematic_extensions

You have more than one "Java Console" mine is 6.0.22, suggest you delete anything older, all of yours appear older, through the Windows Control Panel. Newer updates will delete recent versions but much older versions. get new version at http://java.com/en/download and watch out for install of crapware such as the Yahoo Toolbar see http://imageshack.us/photo/my-images/266/javainstall.png/

You indicate crashes, Crash Reports have signatures

• Firefox crashes | Troubleshooting | Firefox Help
  https://support.mozilla.com/kb/Firefox%20crashes
• Firefox crashes - MozillaZine Knowledge Base
  http://kb.mozillazine.org/Firefox_crashes

Thanks for the reply. Firebug was already disabled and I don't seem to have any other problematic extensions. I have updated the Java Console but also disabled it. I have searched for the signature CreateFileW but it says that there are no results for this. I will see how it goes. Thanks again

It is nearly a week since I followed your advice and no crashes so I guess that it has worked. Thanks again