I did some simulation with geant4.4.0, it simulates some pion+ shoot into some detector, and after several thousand events, the program stopped saying: A, Z, momentum, theExcitationEnergy2 2 (132.721,0,0;136.551) -1880.75 G4Fragment::G4Fragment Excitation Energy < 0.0! The same program runs ok under geant4.3.2.