The whole thing is thousands of lines of code and there's no particular piece that I know to be causing the crash. Before it crashes, the GUI calls routines that run fine as a command line application (in a single thread) and now those routines proceed somewhere half way through.

I guess that it's very difficult to say anything without seeing the code but I hoped that there'd be someone who has had similar issues with opensource Qt, MinGW and static linking. Maybe it's not at all about linking but something to with threads -- or a stupid bug stupid bug that is ignored in Linux/OSX.

Ari