Mac Hangs On Login

Question

This is not your normal "my computer can't log in" type of thread. Its very peculiar set of circumstances, please read the details before suggesting generic fixes:
This is a reoccurring problem. Every few days, this computer will enter into this state where it won't log in fully. The login prompt comes up. When you type in your password, it goes to log in and part way through just stops. The Spotlight portion of the menu bar shows up, but nothing else. The screen is blue. The Eject key will still work, and even bring up the transparent onscreen eject logo. But no desktop/finder/dock will show up.
Running disk first aid and disk warrior have no effect on this problem. Doing an archive & install WILL solve the problem, but it just comes back a few days later.
Apple hardware test did show a problem with the RAM. But after reverting back to the original ram, and then getting all the upgrade ram replaced from Crucial, the ram seemed to have no effect on the problem.
This machine is in a room with two other older G4 macs, neither of which have ever had this problem. I even plugged them all into the same powerstrip, in case the power strip of the problem machine was maybe having electrical problems which were effecting the computer. No luck.
The hard drive is brand new also and checks out fine every time.
Heres where it gets really weird. I found an easier fix than reinstalling the operating system. If you start up the problem machine into FireWire Disk Target Mode, then connect it to one of the older macs, then start up one of the older macs off the problem mac's hard drive, it works. When you get to the login screen, you can log right in.
THEN WHEN YOU REBOOT THE PROBLEM MACHINE, it is now fixed and is able to log in fine. It runs fine until a day or two later when it has the problem all over again.
This machine has the ram upgarde and a new hard drive. It has a firewire burner that is disconnected. As far as software, it has Quark 7.3, and a bunch of older adobe software running in OS 9 via Classic. Thats about it, the printers are network printers, its really a very simple setup.
I've been troubleshooting Macs for a long time, but this really has me stumped. At first I was thinking this was one of those "If it can't be anything else, it must be the logicboard" kind of problems. But then when I found out that you can "fix" it by starting another Mac up off it's hard drive, which shouldn't really DO anything, now I'm thinking this Mac is just possessed

Answer 1

Please post more details. How do you know it is a spotlight problem?
I have this same problem on one Mac. I have found a solution on another site as follows: log on as another account with admin privledges (other accounts log on just fine, it is just this one account that has this problem), delete everything in /System/Library/Caches/ , logoff, the problem account now logs on successfully.
Currently I have that user cleaning the caches directory before she logs off at night, and the problem has not recurred, but I would like a more permanent solution. Upgrading is not an option at this time.
Anyone? Anyone? Bueller?
TIA.
Paul Baughman