I used Applejack happily for several years on pre-Leopard systems, and was happy to have it back. Foolishly, just for fun, after installing it yesterday, I tried it out on my stable, smoothly running MacBook 1,1 (running Leopard 10.5.4). Applejack run with "applejack auto" found no problems, and exited normally. But when I rebooted, kernel panic. Every time I rebooted. Zapping PRAM etc. did not help.

Fortunately, I had a recent Time Machine backup that I was able to restore from using my Leopard installation disk to boot. After a few hours, my system was running again. I have now uninstalled Applejack with "applejack uninstall". Since I don't know what Applejack did that caused the problem (and yes I know that it is running programs built into the OS), the only moral of the story is to make sure you have a full backup and bootable disk handy before running Applejack. But though this was a program that never caused harm and often helped in its previous incarnation, I will wait a long while (and wait for more user reports) before trying it again.