THANK YOU! Sorted now it seems. great!
Glad to know
oh - i've just been back into LR and there are two things that still aren't quite right...?
I can now add an effect in Develop but when I CMD Z to reverse/delete the effect the little black caption box saying 'undo effect' gets stuck in the screen.It's right in the way across the bottom of the photos I'm trying to edit.
Also - I then try to quit - but I have to Force Quit each time..?
Would suggest you to reset Preferences for Lightroom and then, try again.
Also, make sure you have the most upto date version of Lightroom.
Instructions to reset preferences : Resetting the lightroom preferences file - updated - Lightroom Forums