Try restting the cmos and cables.
that worked for me once.

Hey cloud, before the PC shutdown go to
start, run and type CMD
on the black screen type shutdown -a hit enter and you are good to go

Yo malkit what you need to do before it shuts down is to go to..
start-run-and type CMD and hit enter
then on the black screen you have to type shutdown -a and then you are good to go...

when yo boot in safe mode just choose administrator user and will log you right IN, do not hit crt+alt+dlete

What you can do is boot in safe mode and create a new account and give your self administartor rights and then boot back on normal mode.
To boot in SAFE mode just tab on F8 key right after you turn...