Some programs can't connect to internet

I am running Windows XP(with Service pack 2 recently installed, on a Dell 4600. My husband downloaded Netscape and began using it while I continued with IE 6.0. He discovered that if he tried to use IE, it would come up with a Page cannot be found message. Shortly thereafter, our Destop Weather platinum program would come up with a message..cannot log onto server. I my account I can log into both sites without a problem. I am running Norton Antivirus and Personal Firewall, and have checked these out. I also disabled the firewall and antivirus on Service pack 2, though his problem started before Service Pack 2 was installed. I also, regularly run Adaware, SpyBot and Spyware Blaster in the background. Any suggestions on where to look or what to do?