WinXP yields SESSION5_INITIALIZATION_FAILED

When I try to launch WinXP from BootCamp it immediately goes to a blue screen where it says

> A problem has been detected and windows has been shut down to prevent
> damage to your computer.
>
> SESSION5_INITIALIZATION_FAILED
>
> If this is the first time you've seen this Stop error screen, restart
> your computer. If this screen appears again, follow these steps.
>
> Check to make sure any new hardware or software is properly installed.
> If this is a new installation, ask your hardware or software
> manufacturer for any Windows updates you might need.
>
> If problems continue, disable or remove any newly installed hardware or
> software. Disable BIOS memory options such as caching or shadowing.
>
> If you need to use Safe Mode to remove or disable component, restart
> your computer , press F8 to select Advanced Startup Options and the
> select Safe Mode.
>
> Technical Information
>
> STOP: 0x00000071(0x00000000,0x00000000,0x00000000,0x0000 0000)"

However, when I use Parallels Desktop to run WinXP (from the boot camp partition), it runs fine.

Any Ideas?