Looking at the source in Mustang, it appears to be waiting for the
native implementation to callback notifying that the resource has been
destroyed.

Perhaps it is a bug in the drivers. Does it work on other hardware?

OTOH, the code isn't thread-safe at all. It's a mess. The comments don't
inspire much confidence ("It doesn't look like we have a good case of
concurrent programming here.").

It looks like the code you are having problems with is running off an
exit handler. Possibly somewhere JavaSound is trying to create a thread,
which should fail. A similar problem happened when disposing of certain
AWT components attempted to restart the AWT Event Dispatch Thread. If it
is possible, perhaps try closing all the resources before calling
System.exit.

Tom Hawtin