I could find no solution on the net, and too found that in safe mode the boot up stopped at agpcpq.sys.
But actually, the boot does not stop on my computer.
If you have this fault. Try booting up in normal mode.
It will take you past the windows boot up screen and take you to a black screen.
Nothing happens, no disk activity. It appears locked.
I have found - always that after about five minutes, yes, five minutes, the boot up proceeds and completes perfectly.
This will happen one, two or three times on successive occasions.
A couple found a solution for them