Vista - Can not uninstall iTunes 64 bit, why?

I am attempting to uninstall the version of iTunes 64 bit that is installed on my 64 bit Vista Ultimate system.
I am the administrator!!!!!


If I click on the latest iTunes setup.exe,
Get this message:
iTunes + QuickTime in title
The Windows Installer Service could not be accessed.
This can occur if your are running Windows in safe
mode, or if the Windows Installer Service is not correctly
installed. Contact your support personnel for
assistance.
Get this message:
iTunes + QuickTime in title
iTunes Installer

The installer encountered errors before iTunes could be
configured.

Your system has not been modified. To retry these
operations at a later time, please run the installer again.

Click Finish to exit the installer.
I click on Finish and no more dialog boxes.

Per Control Panel -> Uninstall a program -> iTunes

-> Uninstall
Click the dialog box YES.
Get Windows Installer message:
The system administrator has set policies to prevent this installation.
Click OK and get this message:
Installed Updates
You do not have sufficient access to uninstall iTunes.
Please contact your system administrator.
Click on OK

-> Change
Get this message:
iTunes + QuickTime in title
The Windows Installer Service could not be accessed.
This can occur if your are running Windows in safe
mode, or if the Windows Installer Service is not correctly
installed. Contact your support personnel for
assistance.

Click on OK
Get this message:
iTunes + QuickTime in title
iTunes Installer

The installer encountered errors before iTunes could be
configured.

Your system has not been modified. To retry these
operations at a later time, please run the installer again.


Click Finish to exit the installer.
click on Finish.
Get this error message:
Programs and Features in title
Fatal error during installation.
Click OK.

-> Repair
Get this message:
Programs and Features in title
This installation is fordidden by system policy. Contact your system administrator.

Any idea of how to get rid of this?

Thank you.