Hi dvskate86, and welcome to the forum.
A quick bit of research throws up this page;
http://grabii.blogspot.co.nz/2010/05/wh ... ad-x3.htmlLooks like it's a codec for it's own player, which has been recognised as a trojan.
I thought 2.6.3 had everything enabled to allow you to play mp3 etc...however the X3 codec shouldn't be required.
Anyway...open Terminal.
Type "sudo apt-get install ubuntu-restricted-extras" (without the quotes)
Type your password when prompted.
As long as the correct repositories are enabled (which i think they are by default), after the install you should be good to go to play music and videos.
Cheers