I ran the debugger on a different system which had subtly more visible
colors, and FOUND where the system hung.

Remember the code fragment I mentioned before:

	UseReadySemaphore
		ifTrue: [PlayerProcess _ [SoundPlayer playLoop] newProcess]
		ifFalse: [PlayerProcess _ [SoundPlayer oldStylePlayLoop] newProcess].
	UseReverb ifTrue: [self startReverb].

	PlayerProcess priority: Processor userInterruptPriority.
	PlayerProcess resume.

The caret was just before the period in the last line of the fragment:

	PlayerProcess resume^.

Does this help?

-wdc