This tip shows a registrykey that might cause an incorrect error while trying to deploy a RDS environment.
If you have recently patched a server or an other role of feature had been installed and no reboot has taken place, you might run into an issue when trying to a RDS deployment using the Server Manager in Windows Server 20102. In that case the RDMSDeploymentUI.txt log file contains an entry like "Selected server has pending reboots.".
In that case the obvious remedy is of course to reboot the server. If that does not help, check if the key:
"HKLM\System\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations"
exists, if so delete it and try again. Of course it is recommended to back up the registry before doing so.