Create a new profile as a test to check if your current profile is causing the problems. See "Basic Troubleshooting: Make a new profile": * https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems. If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files. See: * http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox See: * http://kb.mozillazine.org/Firefox_crashes * https://support.mozilla.com/kb/Firefox+crashes * https://support.mozilla.com/en-US/kb/latest-firefox-issues If you have submitted Breakpad crash reports then post the IDs of one or more Breakpad crash reports (bp-xxxxxxxx-xxxxxxxxx-xxxx-xxxxxxxxxxxx). You can find the IDs of the submitted crash reports on the about:crashes page. You can open the about:crashes page via the location bar, like you open a website. See: * http://kb.mozillazine.org/Breakpad (Mozilla Crash Reporter) * https://support.mozilla.com/kb/Mozilla+Crash+Reporter * https://developer.mozilla.org/en/How_to_get_a_stacktrace_for_a_bug_report

Do you get the Safe mode start window? Make sure that you do not press the Shift key while starting Firefox.<br /> You can also check the target line in the desktop shortcut to make sure that you do not have the -safe-mode switch appended.

Thankyou to the one who tried to help but the problem resolved itself. Don't ask me how. I simply shut down my computer for a day, turned it back on, and it was fine. Many thanks anyway.