Linksys router setup says it can't find it

Hello,
I just got a Linksys Wireless G router (WRT54GS), using a Charter cable modem, and when I do the Easy Set up install cd, I connect all the cables (from modem to router, router back to modem), I get to the last step where I plug the router in.. it powers up, lights come on (Power, WLAN, Internet, and the Ethernet # it's connected to), but the setup program gives me "Error 344, can't locate router.. make sure LAN cable is plugged in, etc. etc" I may have forgotten the actual error number, but why is this happening? I can't connect to the internet or get the 192.168.1.1 page because it doesn't know the router is even there. I've tried reset button, iprelease/renew, nothing works. I do have a VPN installed to my office, but I'm not connected to that at all when this is going on. Any help appreciated.