Currently Microsoft has been sending "unwanted and wanted" updates to many of the people who received their Windows 8 Pro then FREE WMC key...
entered and then You were 100% FREE - Genuine - Retail Activated....
This patch from M$ has un activated and set many a user to "Not Genuine" status and that leads to 2hours shutdown to black screen...
there are several method to overcome this... but one - If you made a backup copy of your
1. Activation Backup
2. Full Activated Backup Image.
then you can restore back or Refresh Back or use Method #1 or #2 and become Activated again....
then DISABLE all UPDATES...
The Pirates
are have been able so far to patch the patch - tho it is not that easy to patch the patch it is possible....