Hi Rene,
how far do you get before it GPF's?
I have had my fair share over the years. In my experience, if it GPF's in the same place every time then it is something in my app. Random ones I put down to the OS.
GPF Reporter from Capesoft does a reasonable job of tracing the GPF although the log is a bit hard at first. I usually start with this and then add debug code to trace the exact problem. I have traced it back to 3rd party code a couple of times.
HTH's
Kev