Hmmm - You know, now that you mention the keyboard thing, I guess it could be a driver thing, maybe... Just attached a few different things to various USB ports, so I supppose that could have done it if the message popped up behind other open windows I was actually working in when I did that... That does actually make me feel better about that message in general though, as that is a plausible explanation.
Too bad that message is not more specific though - it WOULD save me a lot of wondering.