http://bugs.winehq.org/show_bug.cgi?id=31226
--- Comment #1 from Vincent Povirk madewokherd@gmail.com 2012-07-16 09:36:52 CDT --- There used to be a bug that caused this pretty much at random in Mono, but we think that's fixed now. Also, this is known to happen reliably on the first GC if ptrace is broken (which it might be in recent ubuntu).
Or it could be some other, more specific problem.