Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
• Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

I had this. Found the problem for me was the AddOn "ImageTweak" version 0.22 - I'm running Firefox 3.6.18

I'm having the same issue with a clean installation of this browser downloaded on 05-09-2011

I tried all of this and it didn't work. Someone else posted a solution that worked for me. check your Home page dialog box- I had multiple URLs listed in there, so each time I started Firefox, it would load all of them. It also explained why each time I clicked the Home button, it would reload all of the tabs again. I just cleared the field in the dialog box, put in one address and voila!

Had this problem - Evernote add in was the problem - disabled - sorted.