OS 10.4.5 failure to startup-login window/ black screen/ blue screen-frozen

Question

Hi there,
To anybody that can help me, I thank you very much indeed in advance.
G4 Powerbook, 1.5gHz, 2gb Ram (1gb kingston ram added since purchase date), OS 10.4.5, security update 2006-002 (v1.1 (?) recently installed).
My current problem is that i cannot log into OS X. It boots as far as the login window, which is unresponsive, and then it then flicks to a black screen with 2 or 3 lines of white text and then flicks to a totally 'mac-blue' screen with the black arrow pointer still active.
A history of my problem;
1) Yes, unfortunately I tried to get front row to work on my machine (the hack with the front row enabler etc), and subsequently removed all traces of it after it screwed up a few things (menu bar missing, failure to restart). This tidy-up involved doing something with system library, bezel services...etc.
2) I recently installed the first version of security update 2006-002. i am not saying this is the cause, but sometime after I did this, things started going wrong again. another thing i did recently which i hadnt in the past was to have itunes appear at startup and a few days later i emptied my hard drive of all my music and had this linked to a lacie 250gb via firewire 800. The problem at this was that login/startup was incredibly slow and sometimes the finder would keep relaunching itself on its own once the operating system was up and running. Also, when i tried safe boot, the login window would appear and then it would flick to a black screen. it would let me type in a username, but it would not let me input anything for the password.(I did use disk utility to repair permissions when i did manage to logon).
This whole problem seemed to go away for a day or two, but the login was still slower than usual the past few days.
I then turned on my powerbook this morning and login was extremely long and never completed fully- lots of pinwheel spins, menu bar not loading, itunes not appearing.
After a few forced shutdowns I left the computer for maybe 5-10 mins and it seemed to sort itself out after a few finder relaunches etc, and so i tried a few things;
3) I tried installing the newer version of the security update 2006-002 version 1.1 i think? At the same time i took itunes off the startup launches and also switched off auto login for my account (a silly idea it seems).
Since restarting from the security update, the operating system gets to the login window, which is unresponsive, and then it then flicks to a black screen with 2 or 3 lines of white text and then flicks to a totally 'mac-blue' screen with the black arrow pointer still active.(this is with the power adaptor connected only, no other cables etc)
I have tried Resetting PRAM, and using fsck, although I am slightly unsure as to whether or not this is useful to me anyway. I cannot reinstall the operating system until next week as my mum has my copy of tiger at home a few hundred miles away!
Any help at all would be so greatly appreciated, especially on the eve of my two year anniversary with my powerbook!
Kind regards,
Henry Harker

Answer 1

Hi Henry
I've just encountered this problem with one of our computers at work. Hopefully this will help.
It's a Login Window Prefs problem. It's probably corrupted so you need to remove the prefs file.
1. Startup in safe mode (hold down shift). You should get a login window for the master admin account.
2. Delete the file: userName>Library>Preferences>com.apple.loginwindow.plist
3. Restart.
Let me know how you go.
Cheers
MattD
PowerMac G5, dual 2.5   Mac OS X (10.4.5)