After joining a new Vista install to our W2K3 domain, everything worked fine until I rebooted. Now, (after group policy was applied I'm guessing) there are errors in logs for access denied starting both DHCP service and Diagnostic Policy Service. After manually setting IP, Netmask, etc for adapter, I can browse local network, but still can not get out. Any help greatly appreciated. Thanks.

Doyoumean you can't browse the web? Could it be a DNS problem?

Check you firewall setting make sure that you are not on Public, try pinging the gateway. also move you vista into a new ou with no additional GPO configured