@Snow - IE 7 won't open any site for me, not even at Microsoft. Same with the last 2 versions of Firefox?

The only way I have to access sites or web pages is with an older version of Firefox. I'm using a PC with Win XP that has a Wi-Fi connection to a router that is itself slaved to another router that actually serves as the gateway for my LAN. I did try a wired connection to this main router and it changed nothing. Maybe I have some kind of authentication problem that started early in 2010, before which I had no such problem even though my LAN setup was the same. And Connection Diagnostics shows that I have perfect connections through http, https, and ftp. Go figure!