请大家帮个忙，看看这是什么原因？

在播Media player (or realplayer)时，声音突然没了。昨晚听还好好的。后用BT download了一个电影，今早看时发现没声音了。以前看过没问题的电影，也没声儿了。播放时屏幕信息为：C00D11CD: Unknown error

Windows Media Player encountered an unknown error. This can occur when another program or operating system component encounters a problem but does not communicate the nature of the problem to Windows Media Player.

Error ID = 0xC00D11CD, Condition ID = 0x00000000

请大家帮我解决一下。谢谢。