How to fix corrupted Administrator account or create new admin account in Vista

I have a Windows Vista system whose profile seems to have been corrupted.
Many solutions indicate that you create another admin account, log in as that account, and delete the offending profile information for the account that is corrupted.

Here's the twist:

There are two accounts on this System - 1. Administrator Account 2. Standard Account.

It's the Administrator Account which has become corrupted. Attempts to do any user management / create a new account under the 'Standard Account' leads to UAC prompt for a user/pass. The admin account comes up by default asking for a password (of which, there is none).

When you click 'OK' - nothing happens (no doubt due to the fact that the account is corrupted, so it can't verify who or what is trying to allow the administrative privilege).

Is there a way to fix this account, or create another administrator account to resolve this issue?