Problem on Mac OS X 10.6 with QSound

I have a strange problem on my Mac OS X 10.6 (I've got it both with XCode and QtCreator). I think the problem is connected to the QSound object I use in my software. All the code compiles without problems and 3/5 times it works correctly. But sometimes the software starts and I have this error that freezes the execution:

Starting /Users/MacGiamma/Documents/Workspace/GiammaNoid/GiammaNoid.app/Contents/MacOS/GiammaNoid...
2009-11-27 17:37:11.870 GiammaNoid[6631:903] In '__CFRunLoopLock', file /SourceCache/CF/CF-550.13/RunLoop.subproj/CFRunLoop.c, line 438, during lock, spin lock 0x200b3a8 has value 0x10, which is neither locked nor unlocked. The memory has been smashed.
The program has unexpectedly finished.

Another strange thing is that on Windows (XP) it always works.

The class containing the QSound object compiles without problems with Qt 4.5