Transparacy?

I have an XML Avidyne and XML G1000 set of gauges that for a very small number of people cause CTD's. Usually these people have ATI cards and/ or strange mixes of memory sticks, as opposed to matched pairs. I now have a CTD with a matched pair and a nVidia card. I and our beta testers do not get these CTD's. The gauges make use of XML transparency and also bitmaps with alpha transparency. I'm guessing that the transparencies are the cause of the problem, but like I said, that's a guess. Anybody here know what may cure this problem? cheers, nick