I cant start up my iBook

Question

IT was working properly but then after a day i tried to turn it on, it takes for ages to show the 3 by 4 screen with MAC Os X and a blue strip with prompts changing as it grows, my point is that it stops at "login window starting" and stays there. HOW CAN I GET IT TO WORK?
PLEASE HELP ME!!!

Answer 1

You might give this a try:
You will need to type some Unix commands. If you are not comfortable with this, I don't know of anything other than a re-install. But if you are careful, you should be OK. I recommend you print this out in a largish mono-spaced font so you don't miss any spaces (or add extra ones). Note that case is important.
Be careful. Some of these commands are dangerous, since you are going to be root.
Start up in Single-User mode by holding down the command (Apple) key and the 's' key while you press the power switch. You can let go the keys when you see white text on a black background. When this has finished you will see a prompt ending in '#', although there may be other messages. Type
/sbin/fsck -fy
followed by a return, at the prompt and wait a few seconds for 8-10 lines of output. If the last line says repairs were carried out, repeat this command until you get a message 'The volume <yourdiskname> appears to be OK'. Then continue with
/sbin/mount -uw /
cd /Library/Preferences
rm com.apple.loginwindow.plist
rm com.apple.windowserver.plist
cd /Library/Caches
rm -r *
cd /System/Library
rm Extensions.kextcache
cd /System/Library/Caches
rm -r *
reboot
This should now take you to a proper login screen after the normal boot sequence. You should then Repair Permissions by using Disk Utility (in your /Applications/Utilities folder).
If you get error messages saying files do not exist, note them carefully and just type reboot. Post back to say how far you got and what messages were output.