In twenty five years with various *NIX-based OSes, I've encountered a few of these. You spend hours and hours and sometimes data digging to get to the root of some bug and it feels so awesome when you find the ultimate cause and fix it. Then you step back and say, what did I just do for the last two days? Two days of your very finite existence on this Earth, spent chasing some stupid software bug! I hope that it makes some difference in the grand scheme of things but it almost never does. We fix these things because they are there.