A 'secret directory' that'a a new one for me, must remember that....errrr
And a corrupted file could be any one of many thousands ! (and how would it know to go to a certain directory?)
White text on blue background sounds like a hardware fault, maybe loose or faulty RAM or video card.
I would do a 'service' on the PC, power off and remove RAM, graphics card and any others, maybe lift the processor (with extreme care) and replace it, etc. Then replace everything firmly, double check then power back on and see if there is any difference in the shutdowns, or if they even happen.
(Doing a 'service' like this allows connectors a chance to make a fresh connection)