Can Ping DNS but HTTP traffic!

Hi

I have a problem, I have been using SolidShare for almost 2 years (Ver
2.0x), when I now try and connect to the web via one of my other PC's
over my intanet it says it can't find the DNS server (IE).
I have made no hardware or software changes.

The browser running on the PC hosting Solidshare and has no problems,
but any of the machines using this as a gateway cannot.

I can ping the DNS (on the internet) server from any pc and run a
tracert ok.
But if I try to ping a named web address I get a timeout (This works
ok with the pc with solidshare on).

Any ideas?

Paul