Disable Media Player Update Message

Start/Run/Regedit

'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MediaPlayer\PlayerUpgrade"

Value Name: AskMeAgain, Data Type: REG_SZ (String Value), Value Data: "yes" or "no". Create a new String value, or modify the existing value, called 'AskMeAgain' and edit the value according to the settings below.

Exit your registry, you may need to restart or log out of Windows for the change to take effect.