After working with computers for many years, you get a sort of sixth sense that tells you a computer is about to die. It's the little things you notice: windows freezing, menus taking slightly longer to open than normal, the music almost imperceptibly stuttering.
So when my computer just crashed hard, I had been expecting that to happen for about five minutes. The crash itself was a new one: a critical process apparently died. And, on reboot, it seemed that something bad really had happened, because I was greeted with the message "Reboot and Select proper Boot device". One reboot later and it now proclaimed "A disk read error occured".
Fortuantly I'm rather paranoid about backups ever since we lost a family drive around ten years ago, and so my data is on two separate disks. Unfortuantly, the backup disk seems to act rather like lightning conductor for Murphy: every disk failure since has been a backup disk. Even more unfortuantly, the backup disk is often also my system disk. Murphy does indeed have a sense of humour.
Just to make things more fun, my Knoppix disc doesn't particularly like my SATA controller, and I'm now waiting for a Ubuntu livecd to download to the laptop so I can try something with a more recent kernel. At least it's shown that my data drive is intact.