LINKSYS Router on the fritz…

Greetings all!
I’ve got a LINKSYS BEFSR41 V2 that decided to stop working. It has worked on a Windows XP system for over a year w/no problems. It’s connected through Roadrunner (cable) modem. Basically, the modem & ethernet card in the computer work fine )when directly connected); but when the ethernet cable gets conected to the WAN, and the other cable goes from port 1 (or 2,3,4) to the computer, the lights (100; Full/Col; Link/Acct) simply blink on & off. The computer then states: LAN2 disconnected followed by: acquiring address. back & forth every second or so; over & over!!I’ve tried different ethernet cables…powering on/off…??? What the heck happened here and how can it be fixed?/ Thanks in advance!
James