Hi,
I suggest you check whether you have installed the right codecs
How to determine which codec is installed and how to install it automatically?
a. To determine what codec was used with a specific file, play the file in the Player, if possible. While the file is playing, right-click the file in the library, and then click Properties.
b. On the File tab, look at the Audio codec and Video codec sections. Download and install Codecs by go to the PLAYER tab and check.
c. Connect to the Internet and Download Codecs Automatically.
For more information on codecs refer to the articles below:
Codecs: frequently asked questions
http://windows.microsoft.com/en-us/windows7/codecs-frequently-asked-questions
Hope this helps.
Vincent Wang
TechNet Community Support
