To get WMP 11 to work again in Vista
Disable the User Account Control feature that should sort it as its a pain just google how to do it as im a XP user myself and dont have Vista in front of me.
Ok found it for you
Disable the User Account Control feature in Vista
1# Open Control Panel.
2# Under User Account and Family settings click on the "Add or remove user account".
3# Click on one of the user accounts, for example you can use the Guest account.
4# Under the user account click on the "Go to the main User Account page" link.
5# Under "Make changes to your user account" click on the "Change security settings" link.
6# In the "Turn on User Account Control (UAC) to make your computer more secure" untick "Use User Account Control (UAC) to help protect your computer". Click on the Ok button.
7# You will be prompted to reboot your computer. Do so when ready.
Note: In order to re-enable UAC just select the above checkbox and reboot.