最简单的办法打断点，调测以下。下面是WMPSDK中给你整理的：
a> The OpenStateChange event occurs when the openState property changes value.
Player.openState Possible Values:
PlaylistChanging\PlaylistLocating\MediaLoading\MediaOpening...
b> The PlayStateChange event occurs when there is a change in the playState property.
player.playState Possible Values:Stopped\Paused\Playing...
c> The StatusChange event occurs when the status property changes value.
The StatusChange event is fired whenever this property changes value.