well.well... i have the same problem like your.i use a nForce chipset like MCP65.
and i use an usb keyboard and usb mouse. disable ATA use SATA.it still boot with IoKitwaitquiet() error.after loginwindow seesion started.the screen was black but has singe.about 5min the screen back and show the desktop . i still don't know why for a long time ....