Another ruined flight

I know from the past that there need to be waypoints between origin and destination so that the MCDU flightplan sequencing doesn't crash FSX. But I have still situations where crashes occur, the f-pln page flickers shortly before this happens. Does anyone know what to avoid to not provoke a crash? Last time this occured when I hand flew towards the first waypoint, not following the straight magenta line from the origin airport. FSX crashed when the plane was in the near vicinity of the first waypoint.