sadly I was a little premature in my reply. After adding 6 shots to Redcine, even after restart with reset I now get the same frozen frame for every clip I try to output. UNLESS the clip I want to output is before the frozen frame in the Redcine timeline. Re-organising the clips in the time line makes no difference. In the current example the frozen frame is numbered 1450 but in previous attempts (different projects) the same thing happens on a different timeline frame.
Oh well back to the drawing board