Why not download the latest version of firefox and install it.  It may fix the issue with firefox.  Version 3 .0.1 runs great on my 5 computers.  You should run the latest version anyway so that security vulnerabilities are patched.

I already tried that and the same problem exists.  it will not start.  I deleted the old one and downloaded the latest version of fire fox and same thing

when you say that firefox won't start, are you saying that when you click on it, absolutely nothing happens?  or that it opens, but only to a "blank" page?

 

i'm assuming IE still works normally?

 

have you recently installed or upgraded a third-party [outgoing] firewall, that might be blocking firefox until you authorize its use?

This link tells you how to uninstall firefox more thoroughly, but still even after doing this there may be some registry keys left that could be removed, but I am not sure what they would be.  Maybe if you can get the previous version completely removed then the newer version might work.  Just an idea.  But if ifirefox is starting and you are just not getting the page to load as ky333 asked then it is a different issue.

 

http://support.mozilla.com/en-US/kb/Uninstalling+Firefox