last 2 months, live S FL, USA - colder weather days especially.  In a.m., Nav Panel blank, no control of a/c-heat,radio, etc.  Depending on how cool, screen comes on 1/2 hr later, everything ok.  During day, car sits, start, blank screen, 5 min later, on. (But if car sits in sun, never a problem).   In Sept and before, no prob.  Not sure it's weather related?  (affecting some component).  Car sits in sun, no problem.  2005 S model, only has 70K, is in excellent shape.