Four-body phase-space decay sets incorrect daughter momentum. Occasionally a secondary gets 10^70 (!) GeV or uninitialized (nan).
The error was introduced in version 10.2. The fix will be included in the next patch release.
Patch 2 for release 10.4 included a fix for this issue, as recorded in the release notes at http://geant4-data.web.cern.ch/geant4-data/ReleaseNotes/Patch4.10.4-2.txt o Particles: --------- + G4PhaseSpaceDecayChannel: fixed incorrect indexing in ManyBodyDecayIt(), causing incorrect setting of daughter momentum in 4-body phase-space decay. Addressing problem report #2053.