Paul,
I am using Mbox with Windows XP. It has worked flawlessly. One day I
installed AIM (Aol instant messenger) and Mbox/protools crashed on
every use. I removed the software, and I'm back to flawless operation.

My laptop is a Compaq v2140US with Pentium M centrino and all stock
parts.
I also a P4 desktop that seemed to not like the Mbox. After
reinstalling the Windows XP system and pro tools, flawless.

A couple things I noticed. My Mbox needs to be installed on 1 USB port
and I need to use it on that port. If I started messing around with
plugging it into different USB ports and trying to reinstall on
multiple ports, inconsistent results occured.

Keeping my fingers crossed...

Mike