Looking over some old work earlier today, I noticed that somebody had changed some uses of 'cannot' to 'can not'. I'm pretty sure I wouldn't have used 'can not' originally, because as far as I'm concerned they mean different things:

"You cannot do this" tells you that this is something you are unable or not allowed to do.
"You can not do this" is a cumbersome and ugly construction that logically says that 'not this' is something that you can do, i.e. that you are able to do something else. In my opinion it fails to convey the crucial detail that you must do something else, because you won't be doing this.

Is that just me?

I'll have a word with the editor responsible for the file. It may be that 'cannot' = 'can not' is in the house style.