Vista - Will not power off when installed on Sata HD, ATA install is OK

I have a Soyo KT600 Dragon motherboard. I have been running Vista RC2 on a
normal ATA hard drive connected to IDE1 without problems. I purchased a
SATA hard drive, removed the ATA hard drive and installed Vista on the
single SATA hard drive connected to SATA1. I am using only the Vista native
SATA drivers because the installation program did not recognize the HD when
I attempted to use the motherboard's drivers. The computer will not power
off or restart with Vista installed on the SATA hard drive. I have to pull
the power plug or hold down the power button for more than 4 seconds to shut
down the computer. I tried using the SATA ports as normal IDE channels (an
option on this motherboard) but I ended up setting the 2 SATA channels as a
Raid but only connected 1 SATA hard drive. This was the only configuration
I found that Vista could find the drive and install normally. The
installation proceeded until Vista had to reboot the computer at the end of
the installation.