Does anyone know why I can’t get Firefox 2.0 to launch in XP?

I’m having a very odd problem and it’s driving me nuts. I have multiple
PC’s that are all running firefox 2.0 on the XP OS. I have one machine
though that absolutely refuses to launch firefox. It’s running XP with all
the latest updates, and yes, IE 7.0 is there. IE launches quite quickly
and easily, but I’m not a big fan of IE, yet when I try to launch firefox it
goes to the standard “server cannot be reached” error message. Now
mind you that I’ve at one point had two other machines running side by
side that launched firefox and had no problem, yet this one machine
refuses to launch the browser and it’s driving me crazy! If anyone has
any suggestions on what I can try, any suggestions at all, please let me
know. Thank you.