As of yesterday, cmd+N no longer works. Finder, Firefox, TextEdit, Safari… every program I've tried - when I hit cmd+N, nothing happens. All other keyboard shortcuts seem to work just fine, including other combinations involving the letter N. I'm baffled.
As best as I can tell, this change happened after I ran Software Update and updated to OS X.4.10, and a few other updates (e.g. java). Any ideas?