For some reason, my PowerBook decided not to recognise me this morning and wouldn’t allow me to log in. Eventually, I figured out I could reset my (corrupt) account’s password from the login window using my ‘master password’, but then I wasn’t able to start up to anything other than a blue screen. (Coincidentally, I’d earlier read that one of Mac OS X 10.4.3′s fixes – released today – addressed (an unrelated) issue in which high ASCII characters in a password could lead to a blue screen at startup, or prevent log in.) Previously I’d been able to fix this kind of problem by booting into single user mode and renaming Preferences and Caches folders as detailed in this Apple tech note, but today this didn’t help. I finally figured out I simply needed to reset my account’s password back to match that of my home folder’s FileVault disk image.
Apart from providing myself with a reminder of what to do next time, this post is by way of introduction to AppleJack, an excellent utility I came across today that enables you to run a set of tasks in sequence to repair your disk, repair permissions, validate the system’s preference files and get rid of possibly corrupted cache files, all without loading the GUI.