I Need some Internet Connection Help

[ComputerNut]

Heres my problem: Ive got a Linksys BEFSR41 4 Port Router w/ 2 pc's hooked up: My Dell system and my AMD Athlon system. My problem lies in the Athlon system. lately, ive been having problems getting that thing to stay connected to the internet (Rogers Broadband, if youre wondering). I've tried resetting the router's settings and re-entering all the info, that seems to work, BUT, only for about a day, so i dont think the problem lies in the router. When I tried to right click > Repair, on the LAN Connection icon in Network Connections, It claims that it can't renew the IP address. What should i do?

btw, The Althon system uses XP Pro.

TIA,
CN

[ComputerNut]

*UPDATE* I disconnected a stray ethernet adapter from the router on port 3 that was disconnected from the third PC for awhile now. I then rebooted the system and (after the POST complained of a Power Monitor error, and a second reboot), it can access the internet. Is is possible for a stray ethernet cable to prevent a pc from connecting to the net, or am I reading the wrong set of coincidences?

CN