Could you be running the dark, evil presence known as "Norton Internet Security" ? It seems to do a wonderful job of keeping my friends off the Internet and giving me an excuse to go over and drink their beer...

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8