New install. Installer hangs cold at initramfs prompt.

[Nat Gross]

Hi;
Installing 8.0.4 on new 64 bit HP AMD Phenom9600 system, and a few
moments after indicating "English", the system hangs cold with mouse
and keyboard also locked.
This happens at the initramfs prompt.
Am installing 64 bit on the system which has Vista SP1 installed on
half of 1 drive.
The system has 2 465 gig drives attached to an HP Nvidia RAID
controller but NOT configured as raid, just 2 drives.
It also has a GeForce 8400 video, along with 6 gig of ram.

Please advise.
nat