Occasionally, a client gets the error:
The remote computer disconnected the session because of an error in licensing protocol.
I still have hundreds of licenses in the pool, so not really sure what the deal is, could it be system restore on the client? I don't have the problem on thin clients, just the occasional vista machine or home edition of something, generally a users personal system.
I also use deep freeze on the terminal servers - I don't believe that would cause a issue, obviously no DeepFreeze on the licensing server.