Can not zoom in more! Was possible but now not!

Hi,
I've got an number of Prezis that I have used in the past and edited without a single problem whilst at a number of zoom levels. I must admit I haven't had a need for a Prezi since around October.

So, I re-enter the prezi world today to find out that ALL of my prezi's now have a limited zoom on them and I can't get to the really small stuff - I get the message 'Can not zoom in more'.

However, when I play the Prezi, the player has no issue at all with zooming into that level. What is going on?

I have tried this on 2 machines now, a Desktop PC and an iMac. I have also tried to reduce the resolution of the screen. Nothing seems to make a difference.

Please help!

Thanks,
Mark