Storyline 2 running very slowly

Hi 

I have been having problems running storyline 2 over the past few days. Even when I open a new project and work with one slide using shapes and triggers only, it is running really slowly. I have created other projects in the past and not had this problem. I am working on a standalone laptop and as far as I am aware nothing has changed with the setup. I am the only person who uses the laptop. The problem seems to have arisen since I started experimenting with inserting video and audio files. They are not particularly large media files.

Are there any known issues that could be causing me these problems? I have three projects to build with a deadline and I am worried that I am not going to make it if I can't speed up Storyline somehow.