What's Eating Nick?

11/13/2006 7:34 PM PST
Picture this -- Nick Lachey partying with his hot girlfriend in Las Vegas. Who wouldn't crack a smile? Well, from what we can tell, the answer would be Nick.

Cameras caught Lachey scowling as girlfriend Vanessa Minnillo celebrated her birthday at TAO Nightclub this weekend. Lachey arrived late at around 1:30 AM, missing dinner, and we're told they left together at 3 AM.

Is there trouble in paradise or is it just an off night for Nick? You decide.