In very rare instances, BeOS‘ font settings can become corrupted. You’ll know this has happened to you if you boot up and all you see are little boxes where your letters should be. To fix this problem, you’ll need to delete two files:

/boot/home/config/settings/fonts_list
/boot/home/config/settings/fonts_status

and then reboot. If you can’t see your way around clearly enough to do this, you can either telnet in from another box (if you’re on a network and have the telnet server running), or you can boot with the boot floppy and installation CD inserted, then launch Terminal with [left] Ctrl+Alt+Shift+T.