Help - any router experts out there?

[eve_prime]

R's computer can't find the router. I've checked the grey cable that connects the back of his computer to the router ports, at both ends, and I've tried all four ports. I've tried "ipconfig /renew" and have been told it can't find the DHCP server (the router). The router is most definitely on, because I'm using a wireless connection to it right now.

He did have a couple of copies of a virus, which McAfee found for him this evening, and they've been deleted.

Possibilities - something about his software is messed up? Something about the port aspect of the router? Something about the cable? I suppose if it's the hardware aspect, we could install a wireless card and let him be a wireless person too...