I have a fully updated install of Office 2013 and often use Excel for various things. I’m used to using keyboard shortcuts, but tonight one wasn’t working. And it was one I use a lot. Escape now no longer let me cancel editing a cell. I sometimes do this after pressing F2 for example, which then highlights cells used in a formula. If I press return, it will save as opposed to escape cancel. I prefer the latter as it doesn’t count as a change, and also prevents unintentional edits.
I was starting to get annoyed at this point and hit Google. Various theories came fourth, including F8 extended selection toggle (nope) and sticky keyboard (nope). Then I came across something that sounds so impossible it couldn’t be true, could it? People have reported this happening if you have Photoshop running. I look at my task bar, and yup, I had it still open from earlier use. Closed it, and Escape worked once again 
Does that mean I can blame Adobe instead? I hate them more than I hate Microsoft. I dislike non-standard UI implementations on Windows, although the Office group are usually bad at that too.