I.ve just spoken with my son, who is an installation techniican with DEll
He tells me, fwiw, that you last option is the one he employs whenever he encounters this (rare) fault.
He has been unsuccesful with getting any information regarding the fault from his HO (lol) They muttered something about a faulty image on the hard disk. Apparently a reformat followed by a reinstallation cures the problem - for him, anyway!