After SystemRestore and GPU Change - Cannot connect to any server

[JackHammer]

After a recent system restore AND a GPU upgrade, I cannot connect to any server, i just get connection failed after 4 retries, all firewall's disabled and DMZ'ed through my router and I still get the same repeated problem. Any ideas (and yes, I have legitimately bought GMoD)?

Thanks

[b] Correction: Any game that uses a server browser, all the servers appear correctly but I cannot connect, L4D1/2/Alien Swarm works[/b]

[JackHammer]

Any help please?