Our lab recent moved to a domain with FDCC/USGCB policies and we ran into a number of problems with our client / server configuration. Rather than outline everything, I point you to a link and simply say that the Windows Management Interface (WMI) was the failing point.
From the researcher's client PC (Windows XP Pro) to the lab's server (Windows Server 2003) we found that two easily simulated errors were produce by our previously functioning .NET applications. Power Shell can be used to duplicate the error without having to go into all the .NET WMI code.
PS > Get-Wmiobject Win32_GroupUser -Computer {server} -Credential {domain\server} ...
The first error, "Security Package Specific" error "80070721" turned out to be caused by a duplicate entry for the same server on both the old Domain and the new FDCC/USGCB domain.
The second error, "RPC Server is Unavailable" with the code "800706BA" has not yet been resolved. Any thoughts would be appreciated.
More details at: https://sites.google.com/site/eibflowlab/wmi-work
dgp