Have you checked system event logs for USER32 in Windows itself why its going down ?
If you haven't activated windows then activate it first. I had same issue where licensing service was shuting down Windows sharp after one hour when it was in evaluation mode, this is by design and resolution is only to activate. Check event log closely if shutdown initiated by wlms.exe (Windows License manager service) This will reoccur until you activate windows.
You can extend evaluation for one more count with command slmgr -rearm for the time being you arrange serial key.