Hello, htrebor,
Quote:
If it starts up the computer repair your disk permissions.
It is my understanding that a user boots from the startup CD (the install CD or DVD) in order to Repair Disk, not Repair Permissions.

As necessary, see: Mac OS X – Using Disk Utility to Repair a Disk

Back up everything you can't afford to lose: documents, mail, movies, music, photos, and other data and settings.