Sorry not to come back sooner, but I've been involved in the major project of putting some vhs tapes onto the pc then onto dvds and since most of it was over 2 hrs it had to be split,
luckily most of it was in 2 acts or more.
Anyway having run out of space on drive C I cleared out all the data and moved it to D thus freeing up around 24G of space ran CCleaner and had a good clear up and the problem's gone, so your guess is as good as mine.
Unlikely to be a virus on the mem stick as the only thing it had been in was the portable video player which I think runs xxNIX
I haven't yet made a live cd as I've not yet got my addled brain around WinBuilder, and avast refused to allow make_pe anywhere near the computer.