[Natobasso]

Dump Disk Warrior; you don't need it.

First, repair permissions: Applications/Utilities/Disk Utility/Repair Permissions then restart your computer.

Then if that doesn't do it, put your Install Disc 1 OS X System disk (came with your computer) into your dvd drive and restart while holding the 'c' key down till you see the desktop reappear. Don't let go till you do.

Don't reinstall OS X. What you want to do is go to File/Open Disk Utility so you can 'repair disk'. When you do it from the cd you allow the entire system to be updated/repaired rather than just the non-system files when you repair permissions when booted normally.

Regular repairing permissions is good maintenance and will help your computer run more smoothly if done on a regular basis.

Reinstalling OS X is definitely a last resort in this case and I'd only do it if your system just won't boot up or some other serious issue like that.