BSOD when trying to upgrade XP MCE to Vista Ultimate

Hi,

I am trying to upgrade an XP MCE machine to Vista Ultimate. The XP part of
the install goes okay. However, when the machine reboots, it goes into BSOD.
The message is very generic, and the error code is:

STOP: 0x0000 007B (0x87405BA0, 0xC0000034, 0x0, 0x0)

If I try to do a clean install of Vista (i.e no upgrade) that works.

I do I solve this?

Thanks