Laptop hangs in intervals.

I’m having some trouble with my laptop hanging for about 10 seconds at varying intervals–usually between 5 and 20 seconds. I have worked it down to being related to my ethernet connection as it ceases shortly after unplugging the cable. I’ve checked for viruses and ran checkdisk (XP Pro. by the way) without results. There’s also nothing pertinent in the event log. At first, I thought it was triggered by a specific program, but it continues to “appear” while using various programs. Thanks in advance guys.