i have the same, i install iDebed on my harddisk (SATA Samsung 2 primary partitions 1. vista and second partitions MAC os) all other harddisk disabled (disconnect from bus) and install osx leo 10.5.5 and after setup boot the pc new and the computer starts the bootloader, i boot from harddisk and i see gray screen with an apple logo, and pc stops after 1 minute with this logo http://i6.ebayimg.com/02/i/000/e2/a7/2234_2.JPG (is not 100% the same logo, is gray)

my system

Intel core 2 duo 6750
Mainboard Asus P5k SE
Gforce 8800 GTS 320MB DDR3 XXX from XFX
2x 1024MB Cossair Extreme 800MHz Dual channel
USB keyboard Logitech G15 and Predator mouse
Sound X-Fi creative (for setup OSX disabled)

please help