When you first set up media player, it usually asks you to tick a few boxes about getting information from the internet, like certificates or track listings.
I guess if the right ones were not ticked some functionality is lost from mp11.
Have a look through the wmp11 preferences or options, usually in the tools menu, and then look for network settings, and have a play with them.
If there's nothing like that ( I dont have vista anymore ) then uninstall and reinstall it ? Making sure you pay attention to any installer tick boxes or questions?
Sorry for not being much help
Kind regards