Thanx for all your input, but I may not have described the issue correctly - the sound emitted is NOT a stuck note - it's an electrical drone signal and it's the same pitch each time.
More thoughts came to me from your many comments ...

I will take out the "freebie" styles that are not native to the PA series(they didn't work perfectly anyway), and I will reformat my USB drive for starters.

This lockup is not the same as a note freeze - the instrument is rendered useless and must be powered down to proceed. Mic shuts off sound blares until powered down.
A puzzlement, for sure.