Tried the KATL-UUEE route twice with REX weather.  An hour or two into flight plane pitched up, lost airspeed and crashed.  Third time, everything the same, except no REX.  No problems.

Any thoughts?  I was wondering if REX icing was to blame, but I am assuming the CS767 has heated pitot tubes.  Also I wasn't in clouds.  I am beginning to wonder if REX is causing problems.