Captivate not saving files because of fatal error

Hi, 

I've been having an issue with Captivate. I can't save any of my work without it saying there is a fatal error and terminating Captivate.

As a test, I have opened Captivate, created a new responsive presentation, left it completely blank and tried to save it to my desktop. I get an error message that says 'Unknown exception', I hit retry and a message comes up saying that a 'fatal error has occured and the application is being terminated'.

I have tried uninstalling and reinstalling Captivate, but the same issue occurs.

Please help as I have a really important deadline coming up next week and this issue is an absoloute nightmare!