Sporadic Medialab crashes with Powerpoint

I'm running a Medialab study that incorporates a powerpoint followed by a simple questionnaire. I keep getting random errors involving blank blue screens, powerpoint resetting to an earlier slide, powerpoint slides freezing, or medialab closing unexpectedly. There's no real correlation to a specific part of the study, nor have I been able to replicate the errors consistently. I'm using Medialab 2006 on Windows XP 2002. I've tried everything I can think of, and the experiment works perfectly about 80% of the time. However, losing 20% of our data due to software malfunction is extremely frustrating. Do you have any recommendations about improving stability