Are you trying to play cds or dvds?
Identifying the installed decoder
If you are not sure which decoder is installed on your computer, install the Windows XP DVD Decoder Checkup Utility from the Microsoft Download Center. You can use this utility to:
Identify the MPEG-2 decoders that are installed on your computer.
Identify whether the decoders are compatible with Windows Media Player 10.
Choose which installed decoder you want Windows Media Player 10 to use when synchronizing DVR-MS files to a portable device.
In some cases, the utility will suggest a Web site where an updated decoder might be available.
If the program indicates that you do not have an MPEG-2 decoder installed, consider purchasing one from one of the vendors listed previously.
If the utility indicates that your decoder is not compatible with Windows Media Player 10 and the program does not suggest a Web site where an updated decoder might be available, do one of the following:
If your computer came with a DVD drive preinstalled, contact your computer manufacturer about how to upgrade to an MPEG-2 decoder that supports Windows Media Player 10.
If you installed a DVD drive in your existing computer, contact the DVD drive manufacturer about how to upgrade to an MPEG-2 decoder that supports Windows Media Player 10.
If you installed a DVD decoder from one of the companies listed on the MP3 Creation Packs and DVD Decoders for Windows XP page, contact the company about how to upgrade to an MPEG-2 decoder that supports Windows Media Player 10.
For more information about this error message, in the Microsoft Knowledge Base, see article 884841, "Error message when you try to synchronize video files in Windows Media Player 10."http://www.microsoft.com/windows/windowsme...rors.aspx#index
What dvd burner do you have?
If you do not know, download Everest Home which is a freeware diagnostic program that will tell you.
Download it from here:http://www.snapfiles.com/get/everest.html
Once you know, go to support on the DVD burner manufacturer's site and see if the software you need is available there.