hello,
Grateful for your response.I come from china.
★ My problem: Microsoft MPEG-1 (50) codec Codec is missing.
★ My system:
I have a genuine Vista-OEM, the network upgraded to SP1,
Microsoft Genuine validation through,

WMP is a Window Media Player 11.0.6002.18005,

Recently found to play *. MP3, often Microsoft MPEG-1 (50) codec Codec is missing.Winamp 5.552 normal players! However, windows is the default player WMP. And my Winamp 5.552 is pirated.
★ Issue of process:

Click web help:
http://www.microsoft.com/windows/windowsmedia/player/webhelp/default.aspx?&mpver=11.0.6002.18005&id=C00D10D1&contextid=225&originalid=C00D109B&codec=50
To search for the Microsoft MPEG-1 (50) codec, see WMPlugins.com.
http://www.wmplugins.com/UnavailableItem.aspx?codec=50
Codec not found
The codec you are missing is not available for download from this site. You might be able to find it on another site by searching the Web for "50" (this is the WaveFormat or FourCC identifier of the codec).
searching the Web for "50":
Only: Discuss Windows Media Player 10-Energy Bliss Viz here. 545 replies, have not downloaded! ?
Can not play MP3 files: In the annex
I upgraded the system for Vista SP2, there is no solution!!!
★ Solution:
- Good repair WMP-best
- To set the default Winamp 5.552 Player
Prevent us from my ISP sent a letter to the *** Email address is removed for privacy ***, so the problem does not provide MP3!
Thanks.