Major Leopard OS Bug

I have recently discovered what I consider to be a major bug in the Leopard OS. If you're working on a Mac running Leopard don't do what I did. By changing the permissions on your hard drive to "No Access" under "everyone", it will cause your hard drive to crash. Once you shutdown after doing this, you're Mac will no longer boot! Why would Apple allow a place in their OS to break your computer? Anyway, I didn't realize that this was the problem until after Apple replaced everything in my MacBook, including the logic board, RAM, hard drive and connections. I verified this permissions issue with AppleCare over the phone.