You will need to Reinstall Firefox because your previous Installation did not end properly or it got Corrupted.

-> Uninstall Firefox from your computer - Uninstall your current Firefox

• DO NOT SELECT TO REMOVE USER DATA AND SETTINGS
• Restart your system

-> Download latest Firefox version from one of these links using some other Web Browser:

• http://www.mozilla.com/en-US/firefox/new/
• http://www.mozilla.com/en-US/firefox/central/
• http://www.mozilla.com/en-US/firefox/fx/
• http://www.mozilla.com/en-US/firefox/all.html

-> Installing Firefox

Check and tell if its working.

Hi I have the same problem and have followed the instructions twice and still have no luck, very very frustrating...

@melissah

-> Run as Administrator

Check and tell if its working.

@ mha007 No it is not working have done that both ways as described in the link above in your post...

-> Restart your System in Safe Mode

• http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode

Now follow the instructions mentioned in my first reply. Check and tell if its working.