Joe,
what was tha last tnig you did to your PC before things stopped working? have you installed new firewall or internet security software to your machine?
the most likely cause is firewall software that was aware of your firefox (probably because it was open when the appication was installed) but not the other applications.
the other possibility would be your router (if you have one) that may have reset firewall settings and again was aware of firefox as you had it open when the reset happened.
Are you the only person who uses the machine? could someone else have installed new software?
do you know which day it stopped working? if you do then use the XP system restore facility to change your computer settings back to the way they were prior to the day that the issue started. THis should fix it and give you a starting point from which to find the culprit.
adeyfk
January 2007