Internet drops out

Hello, I have a reccurring, intermittent issue with my internet connection 'dropping out'.
PC running Windows XP with local internet connection via Netgear RP614 V4 router.
When the internet 'drops out' I get a message saying 'a cable is unplugged'.
All cables are plugged in correctly and working. All hardware is working correctly. The fault will also correct itself, at seemingly random times, with no further action or changes made to any part of system...seems to be an issue with the router 'talking' to the PC but I am only a beginner!
Any help appreciated!
Mark H