I am migrating a very old mfc application to Qt. I have installed Qt with the VS2008 migration tools (works fine). I am using the libraries and dll's from the migration toolkit. I am using Run to make an instance of QApplication (step 2 of the migration docs). Works fine in debug, I get the message: First-chance exception at 0x755efbae in pvdev.exe: Microsoft C++ exception: _com_error at memory location 0x0012f6e4.

If I start using debugging, the exception happens at:
> pvdev.exe!AfxWinMain(HINSTANCE__ * hInstance=0x00400000, HINSTANCE__ * hPrevInstance=0x00000000, char * lpCmdLine=0x010130d4, int nCmdShow=1) Line 37 + 0x7 bytes C++

Does anyone have any suggestions? The dll's match versions, paths/environment variables setup, I'm using debug libs for the debug build and release libs for the release build. The project setups are the same except for debugging (though I have to note this is a very old application, migrated through 15 years of operating system changes, so there are bunches of settings/code whose purpose is lost in the mists of time). They both compile/link fine. Driving me crazy, so any suggestions are welcome!