Had to junk my wireless KB yesterday (spacebar broken). On this temporary (very old) replacement keyboard I'm occasionally hitting the Pause/Break key instead of Page Up. No problem in any of the several other apps I've used, but in MEP 2013 it annoyingly zaps all of the tracks. Just black space. I have to use F9 and then change my window size and monitor resolution.
I see no reference to Pause or Break in my KB shortcuts list.
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Terry, East Grinstead, UK