This machine was built about a month ago, burned in using one of the BOINC applications for about 10 days, and generally showed good operational reliability. The computer was installed at the customer location, the BOINC applications uninstalled, and generally showed good operational reliability.
Note that the computer has a 500GB hybrid hard drive, Seagate Momentus XT. Video card is PowerColor Radeon HD 5750. Serial card (which came with unsigned 64 bit drivers, but WindowsUpdate replaced them with signed ones)
As the symptom and sequence is being reported to me, after the computer is not being used for a period of time, the screen will go blank (black), is allowed to remain unused from 15 minutes to about a day, then when the mouse is moved, the Windows desktop appears, the moving mouse can be seen, but clicking on an application will not have an effect. The hard drive activity light will flash regularly (about 1 per second).
What I've done so far:
Power options are set to "High Performance".
Turn off display after: 30 minutes. (have changed this to 0 now)
Minimum processor state: 0% (this was set to 5% while the machine was being burned in, but all cores on the processor were running at 100% sustained)
PCI Express link state power management = Off
USB Selective Suspend = Off
Hibernate = Never
Allow Hybrid Sleep = Off
Sleep After = Never
Slideshow = available
Turn off hard disk after = 20 minutes (just changed this to Never).
Have reviewed the event log, and no interesting error messages were being reported, other than a long string of identical error messages relating to "schannel".
My question: How can I learn more about how or why the machine gets into this comatose state of being technically alive but unresponsive, and how to solve it.
Thank you in advance for your help.