It wasn't quite the same as FSX but with your information, I found the folder more or less where you suggested and loaded the flight plan and it all works now.
I've tried with other flights just to make sure I don't have to go throught that rigmarole of finding the flight all over again and thank goodness I don't!
I don't know now what the hell I've got in the way of PF3,and FSUIPC updates but as it all seems to be fine, I'm leaving it alone.......err....for now!

Anyway. Thanks a lot.
John