Based on the images you provided, there seems to be two concerns:
1) The path to a file you wish to play is invalid, corrupt, or no longer exists.
2) The file you are trying to play is not supported by the player.
Windows media player 7.1 for Mac does indeed play wmv files, however you may need to specify that in the file associations for that particular player.
Unfortunately, I must admit, that I am not very knowledgeable when it comes to a Mac OS, so you may be better off posting this thread in the Apple forum of this website.