This seems to be a common problem and I hope you find the following solution
useful.
Step 1: Backup
Backup all your data, with Vista this is beautifully easy to do
Step 2: Turn user account control off
Start
Control Panel
User accounts
Add or remove accounts (you will be asked for permission, click on Continue)
Go to the main user accounts page (you will find this at the bottom of the
screen)
Turn user account control on or off (you will asked for permission again,
click on Continue)
Uncheck the bok
OK
Restart
Step 3: Make your changes
Step 4: Reinstate user account control permission (if you want to)
Follow the procedure in step 2 but this time you will not be asked for
permission.
I hope this works for you as it did for me. It may or may not be the
approved method and it took me some time to work it out - but it did work.
Regards
Stan
Yo