• This update for Microsoft Windows XP Media Center Edition 2005 enhances the stability and performance of Media Center 2005 and also resolves the following issues: Under certain circumstances, when you watch Live or Recorded TV, the audio and video may not be synchronized correctly.
• When you press the Live TV button on the remote while you are watching Recorded TV, a video, or a DVD, a black screen or an error may sometimes occur.
• If you try to watch Live TV immediately after you complete the First Run Wizard in Media Center, a video error may occur. 
• When you use a Media Center Extender to try to view expired media content, the extender device may stop working correctly until it is restarted. If you install this update and then try to view expired media content on the extender device, an error message will occur, but the extender device will continue to work correctly. 
• After you install this update, the response time for changing or for scanning FM radio stations is much faster.
• After you install this update, the performance for certain PAL TV playback hardware configurations is much improved.
• When you try to change channels in the Program Guide while both NTSC (National Television Standard for Communications) tuner streams are being used by Media Center, an error may occur or Media Center may stop responding. When this problem occurs, you must restart Media Center. For example, this problem may occur if you try to change channels in the Program Guide while two programs are being recorded. This problem may also occur when one program is being recorded and another program is being sent to another location by using a Media Center Extender.

This update is available on the Microsoft Windows Update Web site:
http://windowsupdate.microsoft.com/