Try this solution
http://support.microsoft.com/kb/925704/en-us
PJ
"Sean Anderson" <SeanAnderson@discussions.microsoft.com> wrote in message
news:8BF89911-5C39-4F0A-A886-0E806838CF32@microsoft.com...
> Yep, exact same problem here. And it's bizarre. The hidden instance
> actually still plays media - i.e. if I play an MP3 file, it plays - just
> no
> user interface. Same for a movie - but not user interface - not much good
> for watching a movie.
>
> And I have done the same thing to resolve - kill wmplayer, restart, and it
> works
>
> I am going to check some ideas at home after work, but do you have iTunes
> and an iPod? Was it plugged in? What happens if it is not plugged in at
> the
> time you reboot or come out of sleep? Here's my hunch - WMP is starting
> in
> order that it can manage the iPod, but not much point in that because
> iTunes
> will do that for you.
>
> "Rob" wrote:
>
>> When this happens, press Ctrl+Shift+Esc to start Task Manager, select the
>> Processes tab and you'll find the wmplayer.exe process is already running
>> (although it doesn't appear on the Applications tab). Select it and
>> choose
>> End Process.
>>
>> I've no idea why, but some bug in Vista causes wmplayer to start whenever
>> the PC is restarted or brought out of sleep, but without its window
>> showing.
>> You can't run two instances of wmplayer, and as Vista assumes you're
>> trying
>> to run a second instance when you click Windows Media Player, it silently
>> ignores you.
>>
>>