More messing with the audio demo...
If I select a Midi input device, and then un-select it, I get an assertion on juce_threads.cpp line 185. I doesn't matter if I close the selection window in between or just do it badabing badaboom. Which device I de-select doesn't seem to matter either.
Edit: Should add, that selecting a device and then disconnecting it externally (turning off my USB keyboard or closing seq24) doesn't cause any problemos. It goes away gracefully. It's just when I de-select.
And by the looks of it it's some kind of time-out because I get the please-wait mouse pointer for something like five seconds and then the assertion happens.
Seems to work as of 1.44. Cheers.