http://bugs.winehq.org/show_bug.cgi?id=58696
--- Comment #5 from Esme Povirk madewokherd@gmail.com --- Looks like it might be a deadlock between Mono's loader lock and WPF's WpfSharedBamlSchemaContext._syncObject.
Mono probably shouldn't ever run user code with the loader lock held, because that makes it impossible to avoid situations like this.