strange modem/router problem - help

help,

Windows xp, personal home computer with standard TW rca cable modem
and netgear wgr614 wireless router keeps going dead. All was fine when
the internet went out on my inlaws computer. His laptop also lost it's
internet connection to the netgear wireless router (though it still
saw the modem, it would not connect to the internet). Reset modem,
didn't help. Simply connected the modem and bypassed the router,
Didn't help. Called the isp who did a bunch of stuff through the line
and the modem worked. reconnected the router and all was fine... for
about an hour. Then all internet was lost again. I hooked up just the
modem and it worked for an hour and then it stopped again. I got a new
modem from his isp and did not hook up the router. It seemed to work
fine for 2 straight days. Rehooked up the router and in an hour or so
the internet was lost again. Replaced the router with the same model
and it works... for an hour and then dies again.

New modem and new router but the same problem. What's my next step? If
it's his ethernet card I would think that the wireless internet should
still work with a laptop... but the laptop dies right along with the
main computer. Usually resetting the router works for about an hour
but then it goes bad. This same setup was working perfect for over a
year. I'm far from an expert on these cable modem/router setups but
I've never had a problem before this. Can TW Cable be sending
something through the lines to mess us so we rent their wireless
router? Can cables be going bad? Could the ethernet card be sending
something out to the router to disable it that resetting tem****arily
fixes?
This happens even with no security wep/wpa at all. Any suggestions
would be very welcome.

Thanks
yks