Before I replied to this, I wanted to check lab cases to see if there has been anything similiar reported. While I did find one similiar case, it was for DP 7.03, where the problem started occurring after installing something called vCenter Orchestra. The problem persisted even after this was removed from the vCenter machine, and the vCenter machine ended up having to be rebuilt
You both need to open cases, since this appears to be a systemic problem with DP 8.1 or 8.12. You can get ahead of the inevtable request for information by gathering any entries created in the Applicatiosn Event log or System Event log at the time of the failure, and a set of crash dumps on the machine that is failing
C:\Users\UserProfileName\AppData\Local\Microsoft\Windows\WER\ReportArchive
Note: Where UserProfileName is the actual user profile name.
or
C:\Users\UserProfileName\AppData\Local\Microsoft\Windows\WER\ReportQueue
The easiest method to look for the user mode memory dumps is to go down to CMD (run as admin) or Powershell
Cd\ProgramData\Microsoft\Windows\WER\
dir *.*dmp /s
and
C:\Users\
dir *.*dmp /s
You will probably be asked to provide debugs, but if this were my case, I would be looking for this additional information also