Sorry about the multiple posts, but I have discovered additional information. Windows Media Player version: 10.00.00.3646 Operating system: Windows XP Home Edition Version 2002 SP2 Error message ID number: C00D11CD Windows Media Player encountered an unknown error. This can occur when another program or operating system component encounters a problem but does not communicate the nature of the problem to the Player. Here is what I just discovered. The error only occurrs when attempting to play a WPL file in a playlist from INSIDE Windows Media Player. However, the files play fine when selecting one of the the WPL files from OUTSIDE of Windows Media Player. So, how do I configure WMP 10 to play the WPL files? Any help would be appreciated. Thanks.