How many programs do you have that automatically connect to the internet when you start this computer? Also, what internet connection do you have?
"everyone elses almost stops working" sounds like your networking hardware needs some serious upgrade, except for the fact that yo said its only one specific computer. turn two other computers off, and then turn on the "specific" computer and see if you have the same problem. if you do then its that computer you need to troubleshoot. if you dont have any more probs then you need to upgrade ur network hardware.