Uh, thanks for the heads-up.

Reminds me of a presentation at Interact 2001, where the laptop suddenly interrupted proceedings with that legendary message, “Your computer is now fully charged”. The presentation was about user attention, I kid you not.

And, by way of contrast, how to write good error messages: tell the user what happened, explain the consequences if it’s not obvious, outline how to fix it, explain what to do if they can’t fix it.