With respect, you are suggesting the very things I said I cannot do.
I asked you a simple question, did your friend experiment in Safe Mode ?
If he did not, then he is not very computer savvy.
If he did, then what were his findings ?
There is no point us going round in circles here suggesting stuff your friend has already tried and failed at.
Try looking in Google you will find that this is a huge problem
The reason you will not find anything on google is that there are a million and one reasons why Windows will not boot up correctly. There is no correlation between reasons why Windows will not boot up correctly.
Thus calling it a "huge problem" is a misnomer.
You are just A.N.Other person having a problem with Windows booting up ... sure there may be a couple of thousand other people having the same symptoms as you, but then there are probably a million other people whose symptoms vary.
Good luck with resolving your problem. But if I were you, I'd do what I said, bite the bullet, reformat and restore !
I'm outta here....