segmentation violations in qtcreator, CoGetStandardMarshal

I have a program running in the debugger in qtcreator on a windows 7 64 bit PC with Qt 4.6.2. This program will occasionally crash with a segmentaion violation but with a stack trace showing some dll's , e.g. CoGetStandardMarshal, StgOpenStorage, ComPs_NdrDllGetClassObject, and CoGetCallerTID, then several ???. Because I am not in the midst of a routine that I have called but instead might be manipulating the MainWindow position or sizing, I think this might be related to repainting of either a promoted qwidget or a qgraphicsview that I have images displayed in. But I have not been able to find any responsible code as I am not able to interpret this backtrace. Any hints on how I can better figure out the source of this problem. Thanks very much