odds are the crash IS there in 32bit, you just haven't seen it ... the x64 presentation is probably caused by different heap frag/return/initialisation methods or "parallel execution strategy" changes in that OS - i speak from a lot 32->64 migration experience
It's down to debugging - either walk the stack further down (there's none of your code on it) in WinDbg or use Visual Studio remotely to catch the crash - in both situations, ensure you've got MS Symbols loaded - makes the stack trace more useable -
Symbol Server[
^]
Try turning optimisation off too, specifically for debug, that helps to make the debugging easier