Media player slow to start playing

Need help with Windows media player. When I attempt to play a wmv or wma file it is slow to start playing and while it is waiting I get a message at the bottom left "media Changing" it takes about 20 sec to start. This also happens if I am playing a playlist and skip to the next song - ANY Ideas ???

Found a fix but I don't understand why?
The fix is to go to control panel - sounds - select the speakers I am using - properities - enhancements - disable all enhancements
this fixed it.
I did not have any enhanceents checked -- so I wonder what I disabled??

Oh well I guess another VISTA SECRET .......