I'm on a 15" 2.5 MBP Penryn CD2 running 10.5.3 w/2MB of RAM. Everything's been great, but today I somehow lost all of my preferences. Here are some clues. Anything you can do to help is much appreciated. I was preparing to download something from an FTP using Transmit. I must have clicked on something weird because I got the spinning beach ball. I wanted to give that a minute or so to try to resolve so went to Mail to check some messages. When I went to delete them, they would vanish for a sec, then come back in a different color, and the Delete button in the top bar would change to Undelete (something I've never seen before). I went back to Transmit and force quit. It had been giving me some sort of error message, but a coworker was talking to me at that moment about some stupid crap, I didn't pay much attention to it (though I remember seeing something about "XPanel" or "XSomething" and the option to stop or continue--clicking stop did nothing, clicking continue would close the box and then it would pop right back up) I returned to Mail to see what was up and checked to see if the problem was occurring in one of my other Mail accounts; everything was fine. I returned to the problem account and tried reopening one of the messages that triggered the Undelete and the msg was blank. I went back to the mailbox and no messages showed up. Looked at Mail in Library--the Inboxes for my accounts are all empty. Uh-oh. Quit Mail and restarted. Got the "welcome to mail let's setup your new account" dialogue. Double uh-oh. In addition to Mail and Transmit weirdness, I did get the weird impression, right before the Undelete thing occurred, that while in Mail I had mistyped and accidentally entered some weird key combination. Quit everything (and while doing so noticed a message that Acrobat had also crashed), did a full shutdown of my computer, restarted. All my preferences are gone, my wallpaper is reset to the standard Mac Aurora thing, the dock is factory fresh. The custom icons I had made for some folders are still there, and my identity is still in place also. As far as apps go, everything is still in the folder though, as I noted above, my dock is reverted to out-of-the-box status. All of my bookmarks in Safari are gone-- though they're still there in Firefox. I still get the "Welcome to Mail" message when I launch that. I've tried randomly launching a few other apps. Whereas Firefox started right up, others (DeeJay, MS Messenger, Transmit) act like it's the first time I've opened them, showing me the license agreement and all that. iTunes did the same, and started the create account process, but I clicked "Cancel" on that and my library popped up good as new, w/playlists and all other metadata intact. iCal has a different display than what I had, but all of my appts are there. And there you have it. The good news: all of my files appear to be OK (and I last ran a backup about 10 days ago). The bad: most of my prefs appear to be gone. It's not a tragedy, but it's definitely a major inconvenience. I'm bummed that I had to deal with someone blabbering at me in my office as all of this was happening. If I'd have been paying closer attention, I might have been able to prevent it, or at least provide additional clues. Has anyone every heard of or seen anything like this before? Any suggestions you can make are much appreciated. Thanks.