Press F8 during the restart 'black screen' Choose to create a 'bootlog' Read
this at %windir%/ntbtlog.txt (start/run, type: %windir%/ntbtlog.txt ) The
file should be mentioned by name.
Without any significant error in the boot log, it is probably some corrupt
file in the account you start in. Creating a new account to test might tell
you that. You can run 'eventvwr.msc', and see if anything is obviously wrong
with the system.