Are all of the PCs connected via wired or wireless, to the router?
Have you set the 'Internet Protocal TCP/IP' properties in each PC network adaptor to "Obtain IP address automatically" and "Obtain DNS server address automatically"?
Have you also changed the Internet Explorer options to use your new local LAN instead of dial-up or internet connection sharing with the main PC?
Most likely to be one of the above.
Ade
Giving UKFSN/Entanet a try
DL Sync 4600+ (now 2464 and screwed up by pointless 15db SNR target)
UL Sync 448