Could you try two experiments:

• Start up Firefox with a blank page. Start > Run then paste this and press Enter:

firefox.exe -url about:blank

• Start up in the Profile Manager and create a new profile. Start > Run then paste this and press Enter:

firefox.exe -P

Do either let you run Firefox more normally?

Thank you jscher, the second option worked and it ran fine, cheers for your help.

Hi Spirax, if your new profile works after a restart or two, you may want to start back up in your old profile and use the Reset feature. This is a lot easier than manually copying data to your new profile, although that is another option.

Some reading for you:

• Refresh Firefox - reset add-ons and settings
• Recovering important data from an old profile