Every once in a while, you do something that leaves your computer a quivering slag of goo.
After running every disk and hardware testing utility I have, I’ve come to the conclusion that the problem with my iMac is, well, me.
I tend to install lots of beta software to play with, and I suspect something bit me. Files are vanishing more or less at random (today my keychain went bye-bye, among others).
Time to reinstall Mac OS X and start with a clean slate of applications.
Fortunately, I’ve done a much, much better job of maintaining decent backups the last few months, so the downtime should be relatively minimal.
Once I get the installs going, I’ll be on my laptop working for the rest of the day, with periodic runs to the iMac to swap disks around and start up another installer.