Hello Meghan,
Thanks for the response. In answer to your questions, yes, I do turn on the PXI before booting up. I couldn't find out exactly what type of motherboard is on the computer - it's a Dell XPS 400, and apparently their motherboards are Dell-specific. But I haven't changed it, so the fact that it worked before makes me think that this isn't the problem. The computer freezes within about a minute of booting up, whether I log in or not. It was working for about 6 months until now - I can't think of any changes I made that would have affected it - I did run a system restore to a check point a month back (when it was working), but still no luck. But I stuck the MXI card in another computer and it seemed to work fine, so I'm a bit confused. Would you recommend maybe I contact Microsoft about this?
Thanks again,
Stuart