MacBook Pro late 2011 AMD GPU disable
It is possible that this last one is causing the black screen at boot? - I don't know yet. With verbose mode enable at some point it appears a message relating the reboot to a kernel panic.

Should I move it to another folder? - I've moved it. Don't know if it effects the boot sequence, but the behavior got regular.

Boot to a black screen, press power button to shutdown. Repeat 4 or 5 times. When the message about the panic shows, the boot process runs successfully.