Powerpoint allows editing but can't type any content
I've got a problem with PPT(running mac office 2013) - it is allowing editing but is not allowing any typing, either directly onto slides or into the notes section. It's as though any keyboard functions are not being accepted, as it won't let me delete content either unless I go to edit and cut. I've checked permissions, and no restrictions are set. I've tried googling and looking through various threads, but can't find anything that refers to this issue.
Any help very gratefully received!