This -sounds- similar to the problem I'm having, tho it's hard to tell with so many shutdown problems
In my case when I choose 'shutdown' from the menu, windows shuts down normally, which takes a little time, then screen goes black (no signal), and the pc keeps running
Only after minutes the machine suddenly shuts down.
No idea how to solve it, it's -weird-
Also, choosing reboot from the menu does not have the same issue.
I turned off all the sleep/hibernate options as far as I could find them, even some console command with -h to disable stuff.
(Did that in advance, never liked sleep
).
This is on retail home premium.
Think I'm gonna have to do a clean install on a different drive/partition, see if it's any software/drivers I installed or not