Hi, thanks for the post. It seems that you want to disable UAC function in Windows Vista based on the current symptom. If this is the case, let's follow the steps below:
1. Click Start, go to Control Panel.
2. Choose Classic View on the left pane.
3. Double click on User Accounts.
4. Click Turn User Account Control on or off.
5. Uncheck the checkbox and press OK.
6. Restart the computer.
For your information, you can also check the following articles regarding UAC and its function before turning it off:
http://technet.microsoft.com/en-us/library/cc709691.aspx
http://support.microsoft.com/default.aspx/kb/922708
Hope this helps!
Sean Zhu - MSFT