Re problem file: as any MPEG2 file from any source gave the same result, I didn't think this was necessary. But only on one computer as I have discovered.
Re log file: noted.
Re one core: I had noticed that but had not made a connection. Probably the result of a misguided attempt at fanless cooling a while ago. Anyway, a new CPU should fix the problem or maybe I should save up for an upgrade!
And finally: thanks to the developers for a truly great piece of software and to all who took an interest in this threat.
