Windows 2000 Server

I have a Win 2000 server which had a connection to the internet up until
recently. It is connected via the second NIC card. The first card is
connected to the internal network and the second to the outside world
via a router. All was well until the other day when Norton discovered a
virus and even though it is quarantined the server cannot connect to the
internet. It does however connect to the rest of the network.

Any ideas why?