I had a similair problem with my built in Via network adapter a while back, it would work PERFECTLY 24/7 for months on end then all of a sudden had CRC, dhcp, link status, and card state errors. I have a feeling this might be more to be a drivers/software issue then hardware, but I can't think of a reason it should be happening. If I try to disable said adapter or change its powerstate it will also require a reboot to reenable it(connection failed, stays as disabled). I like having on board network adapters but it seems that either Microsoft or chipset manufactuers are dropping the ball on non-server ones. The board in question happens to have a workstation chipset. Also my brother has had no end of dhcp problems, as well as the inability to even pass packets some days on his NForce2 onboard lan, though he has had no problems with the good old linksys 10/100 adapter.