DEMdev Thanks for catching my mistake. On a side note, now I have to get used to calling the UEM the DEM. I enjoy product name changes as much as a nice root canal at the oral surgeon's office. Hopefully it was renamed for a good reason.
I'd move this to horizon area, but are you sure they are using RDP, is that the default protocol? You can tell in the event log in the horizon administrator console what protocol they are using. I'm not using physical desktops, but I have full clones running in 7.4 and we lock and unlock those all the time and have never seen that. The error message is saying they where using one protocol and then trying to connect to the other one.
I have read recent posts about some of the newest horizon versions using rdp when they wanted to use pcoip, but those seem to reference a recompose operation.
Not sure you got this answered yet but there are gotchas to using physical desktops.
1. Must be Win180x Enterprise
2. Must use blast protocol.
3. Not really a gotcha, but the connection server will try to WOL a turned off desktop, so support for WOL is really a must, or just keep it running.
That's it! You have the other steps down.