Bizarre: Hitachi 7k500 will not work if AHCI mode is enabled

[bashPenguin]

Hey all,

So I just installed Vista Ultimate x64 edition today, replacing Windows XP 32-bit. Installed all fixes, chipset drivers, drivers, etc. and then I decided to hook up my 4th hard drive, a Hitachi T7K500 500 GB SATA drive.

I have all 6 SATA ports occupied, and then when I try to boot the machine, the boot process freezes after saying "Verifying DMI Pool..." and hangs for some time. Then it tries to boot my optical drives, even though I put those as the last priority to boot.

I tried changing the HD boot order so that my Vista drive would always get hit first. No good. I disconnected the other two hard drives except my Vista drive and the Hitachi. No good.

Then I set my machine back using the ICH9R SATA ports as IDE mode, and my system boots fine again. Set it back to AHCI, boot problems come back.

Hardware:
Intel Core 2 Duo E6300
Abit IP35 Pro / ICH9R
Western Digital WD5000AAKS
Seagate 400 GB 7200.10
Hitachi 320 GB
Hitachi 500 GB drive

Right now I am checking the disk with the Vista tool, but it hasn't turned up any problem.

If anyone has experienced something similar, let me know.