Multipoint 2012 Premium - NUServer64 messages and disconnects

Hi Folks,

We are running Multipoint 2012 Premium in a virtual machine on a HP server (2012 Hyper-V)

We experience a number of issues and Google never seems to know anything about the events that are logged.

The clients are Atrust m320 zero clients and from time to time they randomly disconnect and reconnect with different behaviour.

Pattern 1 - All devices disconnect at once, display "Waiting for assigned host" and then come back one after the other. Nothing is logged at all on the multipoint server

Pattern 2 - Two devices go back to the login screen at the same time whilst they are in use. It can be any two devices and the following event sequences will be logged:

"<00616B00_2> Device lock fail." Source NUServer64, event ID 4.
"<00616B00_2> Connect fail." Source NUServer64, event ID 4.
"<00616B00_2> Device does not exist." Source NUServer64, event ID 3.

"<00616B00_4> VGA device not connected" Source NUServer64, event ID 3.
"<00616B00_4> Device does not exist." Source NUServer64, event ID 3.
"" Source NUServer64, event ID 3.

There are numerous other NUServer64 messages logged all over the place, the system also complains about terminal service licensing. I am unsure if this is just noise or indicates that the Multipoint server is incorrectly trying to use TS Licensing - we certainly haven't told it to and there are no TS group policies

Can anyone help me decipher the NUServer64 events? Is there a resource that documents them all for reference?

Thanks,
Colin