http://bugs.winehq.org/show_bug.cgi?id=19317
--- Comment #7 from Dmitry Timoshkov dmitry@codeweavers.com 2009-08-19 00:06:49 --- dlls/winmm/tests/mmio.c has some tests for mmioDescend() and a sample RIFF buffer to test with. Could you please try to at least construct a similar RIFF buffer for the test, or even better add a new test which reproduces the problem?