Emcodec is a Trojan horse that drops and executes a copy of Trojan-Zlob-J, a back door Trojan that allows the remote attacker to perform various malicious actions on the compromised computer.
The Trojan is an installer for eMediaCodec that is a codec for Windows Media Player.
If you can`t uninstall or remove, post to spyware removal forum about your problem.
Related articles: How to remove malicious codecs.