Save Game Problem

Ok, i am in need of some help

I have just went to save my game, on an auto save thing, but when it goes through the process it comes back saying the game couldnt be saved. I have tried saving under a new name and it still wont save

It has also took my original game to a back up save.

What is going on here?

I am useing Steam and the most up to date version

Help would be apricated