Quick rundown: GA-EP45-UD3R motherboard, 4GB RAM, SATA HD and DVD-ROM. Originally had XP installed on HD, wanted to triple-boot XP, OS X 10.5.6, Ubuntu. Tried formatting HD as GUID and Mac side worked fine, Chameleon worked fine, XP had hissy fits and wouldn't start. I reformatted disk as MBR, installed OS X on a USB hard drive, set boot order in BIOS for USB HD first, installed Chameleon 2 on that drive. Worked okay.
Next, I Carbon Copy Cloned OS X to main SATA HD after repartitioning it (remember, it's MBR now). There are four partitions: XP, OS X, Ubuntu, and extended NTFS for XP data. Use Grub-DFE to boot and choose OS X, boots fine. Once inside OS X I launch Chameleon 2 and tell it to install. It does, and it doesn't give any errors. When I reboot the machine goes through BIOS check okay then halts and won't boot unless I use Grub-DFE again.
When the disk was GUID I know the program would use the 100MB EFI partition to store itself and its files. From what I've read I had the impression it would still work on an MBR disk w/o the 100MB 'boot' partition. True or false?