Had a Vista PC that came in with viruses. Got all of them off, but the end result was that the PC would not get out to the net. I could ping, but no browsing. ftp to any site would say "Connection Refused". Ran netsh, reset tcp/ip, flushed dhcp, repaired winsock, nothing helped. Finally, I downloaded Norton removal tool. Removed all instances of anything from Norton Internet Security, etc. Rebooted the PC, and whala!