My Favorite Guides
Answer to "disk permissions database corrupted"You can fix/repair that using the Disk Utility, or reset the user's password using the original install DVD: http://support.apple.com/kb/ht1452
Answer to "Why are my fans constantly running?"This could also be due to a different problem. Check your activity monitor for any processes that run higher than, say 80% at all times. It could even be a bad printer driver with a stuck print job, so maybe you should also check your print queue...