KB Article: http://support.microsoft.com/kb/323497
After you install Windows 2000 Security Rollup Package 1 (SRP1), Terminal Services clients may not be able to connect to the Terminal Services server. You may also experience this problem when you use Remote Desktop Web Connection on a Windows XP Professional computer to connect to a Terminal Services server. When this problem occurs, event ID 50 is recorded in the system event log:
Event Type: Error
Event Source: TermDD
Event ID: 50
The RDP protocol component "DATA ENCRYPTION" detected an error in the protocol stream and has disconnected the client.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
307454 MS01-052: Invalid RDP data can cause Terminal Services failure
The Terminal Services client may also receive the following error message during a connection attempt:
The terminal Server has ended the connection.