Error during bootup

Ok, I am getting a Inaccessible boot device when I boot up into Windows 2000

Server. I have done a check disk on my drives (RAID5) with 3 HDD's. They

seem to be OK per the check disk.

Next I done a Windows repair. After this I was able to get pas the blue

screen and go somewhat into a GUI. It gives me an error saying Security

Accounts Manager initialization failed because of the following error: The

security ID structure is invalid. Error status 0xc0000078.

After googleing this I seen where people said a defrag should fix this. But

other sources point to the registry as a problem. I do have a backup but it

seems like when I load the backup it goes to the same blue screen.

Does anybody know how I can get back into Windows or what else the problem

might be.

Thanks