I tried to replicate your problem briefly with v1.5.2, but no crashes yet. The crashes I had seemed more random.
Edit: Game v1.5.2 just crashed a few minutes in a skirmish game, don't know what triggered it.
I haven't been able to reproduce either of these crashes. Then again, I haven't had that much time to investigate either. I had a report of disappearing carryalls too, which is possibly due to the carryall movement change.
I released v1.5.4 a little while ago and haven't had people throw crash reports at me left and right. Perhaps some of these issues are fixed now? I don't know what could have caused a crash in the first Atreides level though.
I left the debug symbols in in this build, so if you do get a crash, please copy the alert box text.