Linksys dropping connection

[Computron]

I have been trying to fix the setup at a friend's house and am having trouble solving a problem. He is using a Linksys WAG54g modem/router and a Belkin range extender. Just before I installed the extender the internet kept dropping on his computer, usually with the page displaying couldn't find server when trying to access the internet. Sometimes the internet light would go out on the modem and sometimes not. If the connection drops on the main computer it can still be accessed through the range extender. I accessed the modems setup page and changed the dial up to keep alive and for the past week it has held fine until now when it has returned again. I only know a few basics about setting up and tweaking this kind of stuff. Could anyone suggest anything else I could do to keep the connection stable?
The OS is XP sp3 the computer is a small shuttle style, don't know what the specs are. The main computer and the WAG54g are connected directly through cable.
Thanks.

[DeMario]

It may be possible that there is absolutely no problem with the Linksys WAG54g modem/router and a Belkin range extender you are using. I think there is issue with the ISP of yours or the cable which you are using for connecting them with your system. So first of all checkout the connection cable. If not resolved then contact the ISP.

[Computron]

Thanks, that's great. I'll give it a shot and let you know.