BleepingComputer.com: Connectivity issue sporadic

I have a domain setup with 10 computers. 1 computer (XPPro) has started randomly losing connection with the Domain Controller (2k3). Connection goes down for about 15 minutes and then comes back.

During this last outtage I managed to verify that the DC's ip address resolves correctly to 192.168.0.200 when I ping it, but the ping fails. Pinging the work station from the server also fails. Pinging the ipaddress of the DC directly on the workstation fails. Pinging other workstations and the router on the network succeeds 100% of the time. So its only the connection between this one work station and the server which fails in both directions simultaneously.

I see errors in the event viewer basically showing the workstation is losing connection but not why. Things like gpupdate failed or netlogon failed etc.

I've scanned for viruses with MalwareBytes. Nothing. I've set my ip address manually and disabled netbios resolution. I've added the DC name and ipaddress to my hosts file. Any ideas on how I could be losing connection for 15 minute chunks only to my DC from 1 computer?

nevermind. sometimes you just gotta write it down and then 5 seconds later it comes to you, lol.

In this case it was the AVG security suite firewall (which I didn't know what installed) randomly denying the connection to the server. Disabled the firewall in AVG and everything seems good so far.