Some suggestions:
1. See
http://www.microsoft.com/windows/windowsmedia/player/faq/playing_files.mspx;
2. Post about this issue in microsoft.public.windowsmedia.player newsgroup;
and/or
3. Open a free support incident.
Start a free Windows Update support incident request:
https://support.microsoft.com/oas/default.aspx?gprid=6527
Support for Windows Update:
http://support.microsoft.com/gp/wusupport
For home users, no-charge support is available by calling 1-866-PCSAFETY in
the United States and in Canada or by contacting your local Microsoft
subsidiary. There is no-charge for support calls that are associated with
security updates. When you call, clearly state that your problem is related
to a Security Update and cite the update's KB number (e.g., KB954156).
For more information about how to contact your local Microsoft subsidiary
for security update support issues, visit the International Support Web
site:
http://support.microsoft.com/common/international.aspx
PS: My keybord mispels two and it's not a MS keybord