You can change the password of the account you're currently logged in as, but only if the padlock is open under Accounts in System Preferences. I'm guessing that's not the case if it's asking you to authenticate in order to create a new account.
Really you're only option is to boot the machine to an OS X install DVD. On the Utilities menu in the Installer, you'll find an option to reset passwords. You can then select the account on which you'd like to reset the password.
The start up the computer to the internal drive again, log in as that account and have your way with the machine.
On Sep 27, 2010, at 5:39 PM, Rob Ryan wrote:
> I know next to nothing about Mac machines, so if anyone can offer some advice on or off list, that would be swell. Here's the situation:
> One of our departments has a standalone mac machine, which they use for specialized work. The user is on administrative leave and is not contact-able. When this person left, the mac was left running, and running under the person's (admin) account. This is great, in some respects, because the department wants to be able to use the machine. But they would also like to turn it off at night and/or they are developing the reasonable fear that they will do x amount of work on the machine then someone will reflexively turn it off and they'll lose access to all that wonderful work.
> I tried to create another account but couldn't do it without providing the password for the currently-running admin account. Is there a reasonable work around that would allow for the creation of a second account?
> I'm afraid I didn't note the OS version.