apologies for not getting back to you sooner - moved house last week and was offline for a few days too - but Im back now.
Sorry but the pc has been returned so can't finish the steps you suggest.
However believe it or not I now have another one that has the same problem (word gets round) so will go thru the same steps as above to see how I get on.
Is it ok to continue with this thread? (And can I run ComboFix again, or let you know first?)