this is a shot in the dark, but if you installed iTunes you might be running up against an issue with yourwinsock API. The usual symptoms of this problem are either a painfully slow connection, failure to connect to website messages, or frequently dropped connections.

There is a command you can run from a command prompt to reset it (or you can open notepad, paste only this line and save it as a .bat file, ie winsock.bat, then run it). It will call for a reboot.

netsh winsock reset