The first real pride of mine in this area was fixing, well, not really, almost beeing able to fix a bug in... the linux kernel (waouw, tremendous!).

it was about a kernel lockup when booting on some hardware.

I've spent one night a one day investing, adding printk, recompiling, rebooting, pressing the reset button.

it was in the keyboard driver (rocket science, the keyboard driver).

Almost came with a patch (after some guidance from some genuinely nice folks on the LK mailing-list) to notice that

when connecting both the mouse and the keyboard, not just the keyboard, the problem was solved (ohhh shit almost became famous).

I threw away my patch, plugged the mouse, swallowed my pride, and, well, life is not too bad like this either.