No need!!
You just need to delete nvdresman.kext from System/Library/Extensions
I am not a terminal ninja, so do a search on that kext, sure it will pop up
Better if you have another Leo install, quicker.
The music is your welcome screen of first boot, you lucky dog! heheh
hold on... hehehe
No KP's, just that kext that messes with nvidia resolutions and switches the screen to the output device. If you have an extra screen around you can hook it up, create login, navigate to folder, delete kext, repair permissions, and reboot!
I would back it up, just in case.. lol.. but dont fear - DO IT !
EDIT: Just noticed you dont have nvidia card. But the symptom is sooooooo similar, I bet its that kext doing the funk. Try it out, it wont corrupt you install, and its an NVIDIA kext anyways, so it shouldn't even be doing anything - safe to delete