You cannot play MPEG4-encoded content in Windows Media ... http://support.microsoft.com/kb/835861

When you encode MPEG4 content on dual processor computers or on computers that support hyper-threading, an incorrect flag may be set in the header of the content file. Because of this incorrect flag, Windows Media Player and various devices cannot play back the content file.

C:/Windows/system32/WMVDMOE.DLL is Not Present