I found I needed to do more than just turn off the visual notification. You have to turn off all error messages.
I did this
I may have tweaked some other things, but I know that one of the tweaks, I think the second one above, disabled all error messages including error messages like the ones asking you whether you want to save a changed document when you close Notepad. I never found this to be a big problem, and in some ways I liked it, but it may mean you have to be careful about changes you make to text documents. One simple way around this is to stop using Notepad and change to a much better text editor, such as NoteTab