Tried deleting deformers, didn't make any difference. :( 

@ Jules53757 - thanks for your suggestion.  The strange thing is that the distortion doesn't occur on the base version of V4.2, or Elite, with ++morphs ....only on A4/G4 (and then only where I've used an old 'amalgamated morphs' cr2!), so there can't be a problem with either V4 or ++morphs.  It also only happens in P8 and PPro 2010, not in P6/7/PPro7 or DStudio 2.3 and 3, so that's another indication that there isn't a need to reinstall.  I DID  try reinstalling A4, to see if that made any difference, but it didn't.........:(