Pinging- open a command prompt and type "ping <ip address>"
Normally your router will have IP 192.168.2.1 and your CM will have address 192.168.100.1- try pinging both of these addresses.
Is it the standard
www.ntlworld.com homepage- or is it
www.outbreak.ntli.net?
Otherwise have you virus / ad-ware checked the machines, and are you still running firewalls (inc. XP's own) on any PC- as iirc your router will have one already.