The following are some of the commonly seen symptoms:
- You may be limited in the number of users who can connect simultaneously to a Remote Desktop session or Remote Desktop Services session.
- You may have a port assignment conflict.
- You may have an incorrectly-configured Authentication and Encryption setting.
- You may have a certificate corruption.
- Server 2003: http://support.microsoft.com/kb/2477023
- Server 2008: http://support.microsoft.com/kb/2477133
- Server 2008 R2: http://support.microsoft.com/kb/2477176
Additionally, we have more symptoms documented in the following Microsoft TechNet article:
Troubleshooting General Remote Desktop Error messages