Run the app with the /pbdebug command line option. You'll get a trace file that can be used to find the last statement executed, and you can backtrack from there (or see if last line caused the problem). Debug file will have the same name as the exe, but with extension .dbg instead of .exe.
Best guess, without knowing what your application does, is that you're making one or more external dll calls, and something about that dll call has changed. Possibilities are:
- Windows has a new problem with the return stack (rare, but not impossible)
- At some poing you had code to work around a known dll problem that's now solved
- A structure used with an external dll call is now a diff size and you need to change to match it
- The return value from the external call is no longer as expected and causing code issues
Without knowing what your code is doing, it's hard to pinpoint what your issue may be. Give us some more details and we can probably help.