Windows 8.1 is brand new to me.  And I've just gone through a "crash" course  in error diagnosis, correction,  and systems management.  My knowledge of Windows XP goes pretty deep, learned through the trial-by-fire of keeping my WinXP system running under a daunting load of functional software and continuous testing of new software.  (I know it's time to leave WinXP, now that Microsoft has ended support.  But the migration problem is a topic for another day.)