Windows Media Player can't open the file.
Things to try:
If the file is currently in use, close the file, and then try again.
Make sure that you have the appropriate rights to the server or file location, and then try again.
Make sure that you have the appropriate rights to the proxy server, and then try again.
If you're trying to rip a track from a CD to your hard disk, make sure that you have the appropriate rights to the hard disk location, and then try again. If the problem persists, try ripping to another folder.
Depending on the version of Windows Media Player you have, either click Organize, and then click Options, or click the arrow below the Rip tab, and then click More Options.
Click the Rip Music tab, and then click Change.
Select another folder in which to store your digital media files, and then click OK.–or–Click Make New Folder, enter the name of the new folder, and then click OK.
If you're trying to open a playlist that is stored on a network drive (such as on a hard disk that is installed in another computer) and the items in the playlist are also stored on a network drive, do one of the following:
Using Windows Explorer, move the items in the playlist (that is, the files that the playlist points to) from the network drive to a local drive (such as a hard disk installed in, or directly attached to, your computer).
Using Windows Media Player, create a new playlist that includes the same items as the old playlist, but store the new playlist on your local drive instead of on a network drive.
By default, playlists are stored in the My Playlists folder. The My Playlists folder is typically located in the same folder where you store tracks ripped from CDs. To change the folder where you store your playlists, you might need to change the folder where ripped tracks are stored (see the procedure described earlier).