If you spend a few minutes to setup GFlags... you should quickly find the source of the heap corruption.
Where to get GFlags[^]
This is a very powerful tool... and you will become a much better engineer if you learn how to use the Windows debugging tools. Note that GFlags is not just for kernelmode... you can enable per-process heap monitoring in usermode processes:
Detecting Heap Corruption Using GFlags and Dumps[^]