Hey Reschke!
Technically, you should have 3 accounts. Your user account (which probably has "admin" privileges), and your second user account for her. The third account is the actual Administrator account. You only access it when you go in through safe mode (or at least thats the only way I know of to get into it).
If you dont have this, or it got deleted somehow, perhaps that is your problem? Even the user account with "admin" privs isnt as complete as the actual Administrator account (at least I dont think so, I've never really had a need to test that).