On the PSM Details | General tab under an Account there is an option for "Enable Console Connection?". What does this option do?
This option controls whether the RDP session is opened with the console option, and is equivalent to running "mstsc" with the /console (in Windows 2003) or /admin option (in Windows 2008). These options open the RDP session 0, which is as if the user were sitting at the physical console of the system.
If you are not running Terminal Services and using admin RDP logons you would normally select this option. Please note, if you are not using this option and are not using Terminal Services, Microsoft only allows two non console concurrent RDP connections - even if these connections are inactive. You can check session usage in Terminal Services Manager.