RPC error opening user manager on BDC

In one of our sites we have a BDC and a few member servers in our domain. When we try to open up user manager on the BDC we get an error “The Remote Procedure Call Failed”. If we try on a member server we get in, but it takes a few hours to reflect the changes. We are connected to the PDC through a T1 going through a Bordermanager VPN. No other office has this problem.

Thanks,

David