System Preferences Zero KB

My System Preferences is not working from clicking the link under the blue apple drop down menu. I went and checked the application under the Applications folder and it exists, has no icon and has a size of Zero KB. I tried using the Pacifist method of extracting the System Preferences.app from my Mac install CD and replace it with the one from the Applications folder, but I get the grey screen of death and a message telling me to restart my computer every time I try to remove/move/or rename the Zero KB System Preferences.app.

Adding more mystery to it, I know for a fact that I never edited or removed or did anything to my System Preferences.app and it was working yesterday, the only change is that I installed the Quicktime Security Update and the iTunes 7.2 Update.

Please Help,
Jake