internet access

[boofhead]

Having a spot of bother with connection to internet. I have a cable modem built in to the computer and it is indicating that it is working OK by the lights it uses to show such things, but the computer, if left idle for a while, will not connect. I have to shut down the computer and start it up again to resurrect it and allow for it to go on line. I am using Tiny firewall, have used Zone alarm and the XP firewall, same thing. But now the problem is worse than ever, and if the computer is left idle for as little as 10 minutes it refuses to connect. Does anyone have any guidance for me to trouble shoot this exasperating problem? It is driving me bonkers, and seeing me bonkers is not a pretty sight.