What bug can cause zero score?

Recently I noticed some very very low score, some are run on my machine, none of which can be reproduced even with thousands of rounds. However, when some exception is thrown in one round, it will only affect that round.

Then if the zero score is caused by uncaught exceptions, it must be thrown in every round. What else can get my bot disabled in every round? It seems that my bot is not firing even one bullet, or moving even one pixel, in the rest of rounds.

I had this problem about one years ago and I fixed it by finding an infinite loop that doesn't use getXXX() or setXXX() methods. Another thing I did was rewriting everything again starting from the last version.