Odd one this....
I am in the process of installing a new AV system onto my Server 2003 box (this is our only server and performs all the usual roles)
During this install, I have discovered that the server has no Internet access at all, despite the fact that it runs the DNS for the LAN, all LAN PCs have normal net access and the server itself resolves DNS queries with no problems.
I've checked with both IE and Firefox, neither are able to load any webpages, both give a "page cannot be displayed" error.
Any thoughts as to what might be causing this?