I think you have a spy/ad-ware problem if you are using windows, expecially windows XP without SP2. Try running 'ad-aware' and/or 'spybot search and destroy' to remove all of the spy and ad software. A friend of mine had the same problem with thier connection. And the cause of it was a malicious program running that hijacked their connection for a few mins while it up/downloaded whatever. This might not be your problem but it won't hurt to check.