This is gonna be a tricky case, so put your thinking caps on
.... This is gonna be like a Mystery Diagnosis but for computers.
Internet Drops Every 5-3 Minutes, for 2 seconds tops maybe.
Logs off messengers,MMORPGS,Downloads, anything up.
Happens to only 1/8 computers in the house.
Not a virus, reformatted last night (happend before format too)
Not a either net card problem either, changed it an hour ago.
Don't use limewire,kaza,bearshare either.
Now you know the symptoms, so, whats the problem =) Come'on doctors!