The error code is common and there are a lot of things it could be....
#1 - The file is corrupted (although, in this case, you're more likely to see error code C00D080D).
#2 - The file type is not supported by Windows Media Player. For a list of file types (formats) that are supported by the Player, click here, e.g. you are trying to play a Real audio file and so will need the Real Audio player, or you are trying to play a .mov file and so will need the Apple media player.
#3 - The file type is supported by the Player, but the file was compressed by using a codec that is not supported by the Player. For more information about correcting codec issues, see the article "Codecs for Windows Media Player"
#4 - The file type is supported, but you are trying to play it in a way that is not supported by the Player. For example, you might have tried to drag a DVD file with a .vob extension from a DVD to the Windows Media Player icon. Or you might have tried to open a .vob file by clicking Open on the File menu.
#5 - You are trying to play one part of a multipart file. Use a newsreader or other program to combine the files, and then try again to resolve error C00D1199
#6 - You are trying to play a DVD and do not have a DVD plugin for Windows Media Player.
More than likely it is #2 and the file format isn't supported. What kind of file is it?