Three suggestions:
1. If Firefox will boot up at all, go to this link (or you can open it in IE):
Read it and disable any add-ons/extensions you have and see if it will work. If it does, you will have to find and disable the offending extension (my problem was with either Adblock Plus or No Script - I didn’t bother to check as it was for a one-time view web page and I used IE).
2. If you have a home page (mine is FR), you might want to have it start with a blank page until you figure out the problem (Tools>Options>General>Startup - blank page).
3. Once you get it running again, go to Tools>Options>Advanced>Update and check the second box (check for updates, but let me decide to install them).
Good luck!
Thank you... I’ll give that a try ASAP.