Excellent tool for troubleshooting & repairing a number of issues on a Mac, all from 1 place. Especially if your Mac won't boot into GUI mode and/or you don't have an install/repair disk. You could perform basically the same functions with other programs or from within OSX itself (Disk Utility or /sbin/fsck -yf in SU Mode for instance) if it's bootable, but w/AJ you can do it all from 1 place. As far as the review I read about the interface being "too simple and outdated" umm... it's SINGLE USER MODE! Ya know, command line, text only, etc. (i.e. terminal/DOS)? Heck, you even get a few different colors! What else exactly were you expecting??? Anyone familiar w/UNIX or even DOS would see this as a pretty darned good interface. As far as functionality, it's a great set of tools & very easy to use. Be sure to install MEMTEST w/it, even if you're not planning to use it right away, in case you need it later. Also, make sure you know what you're doing before jumping in right away & running everything in Auto-Pilot mode ("applejack auto restart" or shutdown) as you can end up doing more harm than good if you're not careful (be sure to read/print out the READ ME file). For example, I usually skip the "validate preferences files" altogether, but this is especially true for Auto-Pilot. This runs the "plutil" command to check the files in /Library/Preferences, but is not that exacting & can remove files that aren't actually bad. Additionally, when in auto mode you can't check user-level items as you can in Interactive mode. Finally, there is a "Deep Clean" mode (accessible by typing "applejack AUTO" {AUTO in all caps}). This will delete ALL cache files, which may sound good in theory, but it also deletes the cache in the Launch Services folder. This will result in resetting the custom file associations (which applications open which files) you've configured, as well as resetting the security dialogs that pop up the first time you launch a program by double clicking an associated file. The only time you should really choose this option is if you have a related issue that the standard mode didn't resolve. For what it's worth, my advice is to boot into Single-User Mode, type applejack & just run the utilities you need interactively- 1 at a time. This way you can not only see what's going on, you have the ability to perform user account specific tasks. Also, skip "validate preference files" altogether unless you're having a problem related to a corrupted preference file; there are also other tools out there that do a better job as far as preference file issues. Otherwise, this 1 of my "must-have, install immediately" utilities. I hope someone finds this review helpful. WhiteHatH4x0r Cyber-Security / Intelligence Analyst