I've been using (for 2 years) linksys SRX 200 wireless router. I just stopped getting the internet signal one day. I can still find the router in my Intel ProSet Wireless manager. I can also get the internet signal when I plug into the cable modem directly. It seems the problem is between the cable modem and the wireless router. (Yes there is a cable plugged into both and I've tried swapping out cables as well.) What could be causing this problem?

What I've found with my wireless router is that dust fouls things up quicker than anything else. It causes my router to overheat and then it's unable to get it's IP info from the modem.

My "fix" is to shutdown the router clean as best as I can, let it cool down for about 10-15min and then restart it.
That just my case though and yours might be something completly different. But you could try that and see if it's a work around for you.

Have you tryed accessing the router to see if it is getting the IP address from the modem when the internets not working?
That could halp to lead to where the problem lies.