Desktop will appear to become unresponsive to the end-user, but if you look at the VM console, you will see that it's actually blue-screening with STOP 0xA. Analysis of the dump file will point to unirsd.sys.
This issue has been fixed in the most recent versions of App Layering (4.3 and above) and Unidesk (2.10.2 and above). Please upgrade. If you continue to get STOP 0xA blue-screens, please generate a full Windows Dump file and get it to Support for analysis.