Admin accounts turning into standard

Hello all,

At my work, we use Macs running 10.6.8 . Recently I have run into a strange issue on a coworker's computer. Her computer is magically turning any Administrator level accounts into Standard accounts. I've already tried that trick where you delete a file to trick the computer into think you haven't set it up so it'll play the Welcome animation and let you create a new account. Unfortunately any account created that way automatically becomes a Standard account.

I then enabled the root user account. I still couldn't make a separate Administrator account that way, every time I tried to check the "Allow user to administer this computer" box in accounts, it would only stay checked for a milisecond before unchecking itself. So, for a while, the root user account functioned as an administrator account. Unfortunately, today, I discovered that even the root user account has morphed into a Standard account!

What the heck is going on with my coworker's computer? Is there a virus or something? How do we fix this?