[magic_haze]

Not completely unambiguous, though. I've seen plenty of software with negations in their dialog messages ("Don't delete x?") Particularly egregious with driver installations. Everything considered, buttons with actual verbs seem the most foolproof.

[rhizome]

When would someone ever need to confirm not doing something?

[potatolicious]

Considering Windows used to have an "Error: no error" dialog somewhere, I'd leave nothing off the table...