Ir a:
Start–>Run–>secpol.msc
Security Settings\Local Policies\User Rights Assignment
Right pane –> double-click on Allow log on through Remote Desktop
Services –> Add Users or Group –> enter Remote Desktop Users
Start–>Run–>services.msc
Look for Remote Desktop Services and make sure the Log on account is Network System, not Local Service.
Check your event logs.
gracias serverfault.com
