His profile may be damaged. This link may help,

Troubleshooting terminal server issuesBlack screen while connecting to TS "Because of a network error, the session will be disconnected. Please try to reconnect" ...
     http://www.chicagotech.net/troubleshootingts.htm

Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net 
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com 
 Good Day,

 I am having a strange issue with one pc.  I can remote into this
 desktop as administrator for the domain login via XP RDP client.  The
 primary user of this desktop cannot login even though he is setup
 identical to my profile.  If I try to connect via remote desktop under
 his profile the login window freezes and then clears the screen maybe
 30 seconds later.  The firewall wall exception for remote desktop is
 in place and works properly for the administrator to login.  This
 users domain account is set within the remote tab, remote users
 enabled.  There is nothing being logged in the system or application
 log during these failures.

 Regards,

 Richard