Just returned home from a trip during which my Intel iMac running 10.4.10 was left shut down. It was running fine before I left. Now, I am unable to log in to my primary admin account. I just get a generic desktop background after typing my password. No menus, Dock or anything else except the mouse pointer. I then tried logging into some other user accounts I have, and that worked briefly, but eventually things started freezing up in those accounts and I had to force a shut down. Booting in safe mode made no difference. I ran Disk Utility from my install disk and it found no problems. I also repaired perms while one of the other accounts was working, and I even used Diskwarrior to rebuild the directory. Finally, I tried moving the com.apple.loginwindow.plist file out of the Preferences for the account in question. Still no luck. Any ideas?

Since the problem follows you to other user accounts, that suggests some kind of system-wide problem. Since it persists through Safe Boot, that rules out a problem with some third-party software, such as a font manager program or a driver.

So, let's try narrowing things down a little.

If you try to log in, when the computer shows the desktop and then hangs, can you bring up a Force Quit dialog by hittng Command-Option-Escape? If so, does it list any programs running?

No, hitting the force quit keys does nothing. However, the system is still functional enough that it the screen dims and then sleeps, and it wakes up when I press a key.

OK - I have more information. I logged into another user account and ran console and Activity monitor. After a few minutes when things ran normally, Console showed that "coreservicesd" crashed, and Activity Monitor showed that the Finder and Loginwindow were not responding. I also could not switch apps via the Dock, could not bring up a force quit dialog, and could not shutdown via the keyboard.

I seem to have solved the problem. After more research, I did the following: 1) unplugged the iMac power cord and then plugged it back in and 2) rebuilt the launch services database using Cocktail. Things appear to be back to normal. Thanks for your attention.

Thanks for keeping us posted; I hope your fix sticks.

For future reference, it will be in your and everyone else's best interests if you try fixes one-at-a-time, rather than in gangs; that way you'll know precisely which one worked.

You're right, of course. I normally follow that advice but I ran out of patience this time.

I can certainly get behind that; there are times when I'm troubleshooting a problem when I reach a point I stop caring about the exact cause of the problem and just want it to go away.

If coureservicesd was crashing, it's probably dumping the caches that fixed the problem. Among other things, coreservicesd provides icons for folders and files and provides information about the relationships between files and applications, and it can hang or crash if some of the cached information in the Launch Services database gets mangled.

I can certainly get behind that; there are times when I'm troubleshooting a problem when I reach a point I stop caring about the exact cause of the problem and just want it to go away.

I hear that. I got over that about a week after I started working on computers.

Archive and install and combo updaters fix a world of hurt not worth tracking down. The trick is to get a feel for when a general fix is a time saver... will it take less of my time (of actual hands-on-the-computer) than the fix, and what are the odds that it fixes it.