As far as I can tell, mstsc.exe.MUI goes on a Vista machine. This make use of the Windows XP TermService. The Service in tern depends on the RPC Service running, which should already be on Automatic. The TermService is used by the Fast User Switching Service.
You will need to check the state of these Services and determine if the mstsc.exe.MUI should be on the Windows XP machine.