If you are getting an Error 15 in your player, it often means that you need to re-install or upgrade your Windows Media Player.
Please follow these steps. You have to perform both in the order specified for this to work.
1) Go to: Microsoft Codec Site - download and install new codecs as instructed on page.
2) Go to: Windows Media Site - and reinstall WMP 10 from the page by clicking open in the download dialog box (be sure to close ALL Microsoft applications including IE when installing).