Macbook air powerpoint presentation menu bar disappears when switching to Slide Show

I have a MBA and ive had office as long as i can remember. I do presentations quite often using Powerpoint. Its an MBA 2011 and Office for mac 2011 as well. It always worked just fine.

A few months ago I noticed that when I try putting the presentation into Slide Show, the top Powerpoint menu bar disappears and it seems like its going into Slide Show mode, but nothing else happens. Specifically, the presentation doesnt go full size on the screen.

I dont have an external monitor connected, dont have more than the 1 desktop setup, and its not in FULL SCREEN mode as Ive tried Command-Control-F. I dont know what is happening but its not full screen slide show mode as it used to be.

In the image below the Slide Show button on the bottom left has been clicked, the top menu bar has disappeared, but the presentation in clearly not in Slide Show mode. If I do Command-Tab to another app and then back to Powerpoint, when it comes back to power point it shows a black screen for about 1/2 a second as if it was switching to slide show mode but then it just displays the same screen as in the image below.