The remote computer disconnected the session because of an error in the licensing protocol. Please try connecting to the remote computer again or contact your server administrator.

This appears to be caused by a corrupted Registry key on the user's PC, I was able to recreate the issue on a Windows 7 machine by deleting the below key. It should be fixable by importing that key from another PC. A Registry backup should obviously be taken before making any changes.

Location:    HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing\HardwareID
Key:    ClientHWID
Type:    REG_BINARY