After starting RRAS can't use remote desktop do access domain server(2003R2)

[Potone]

Good evening.
Win 2003 R2 x64 server running as domain controller.
It worked fine until I tried to configure RRAS.
Result:
no remote access via terminal services to the server
the server doesn't accepts any try to join the domain by new
workstations (even giving Administrator and correct password)
extremely slow to autenticate login requests by workstations in the
domain

Thanks for any advice
Matteo