Excel screwed in Panther

Hi guys, I've got a bit of a problem with Excel. I can only assume it's after I installed Panther yesterday.

In my spreadsheets I don't appear to have any decimal places in any of my cells! This is messing up all my graphs and none of the cells are formatted correctly! I really don't need this because I have to show my tutor all my data so far on Monday!

Does anyone else have similar problems? I'm running 10.3.1.

Oop! It's fixed! I should have known just to completely quit Excel and relaunch it. Everything's fine now. Something must have corrupted somewhere...