I had a very similar problem some time ago after a power cut, only the first PC to finish booting would connect to the net but all worked individually when connected straight to the modem. The problem turned out to be that the router had reset its own IP address to the same as the cable modems internal one. Took a couple of days to work out cos it didnt even occur to me to actually
look at that one on the tables
as I thought that duplicate IPs on the same network would stop all trafffic. Once I'd reset it a quick reboot of the PCs and everything was sorted
