Group Policy/RSOP Problems over Network

I’ve had a problem with RSOP. I can’t use the GPMC to do a RSOP check on my
domain client computers. I get an error stating that I should make sure that
WMI service is running on the client (it is) and it goes on to state that
“The RPC server is unavailable.�

I’ve searched high and low for a reason why this happens and I can’t find
anything. As far as network operations go, I can ping the server from the
client using both the server’s ip address and the server’s host name. The
strange thing is that I can’t ping either the client’s ip address or host
name from the server.

I’m running a Server 2003 network with Windows XP Pro client computers.
When I check the client settings (on the “test machine�) I see that WMI, DNS
Client, and RPC are all running and are set to automatic. I have DFS running
on the network. I’ve gone though a bunch of KB articles and haven’t found a
solution that works for my problem.

Any help would be greatly appreciated.