Norton Anti-Virus will not remove security risks.?

Scan reveals "Downloader.MisleadApp" "Trojan.Zlob" & "Trojan.Zlob.N". Results window says "Cannot remove from an unsupported file." What’s that mean? Action window offers only one option: Review. I’ve followed directions in the review section for removal, but it does not work. http://bit.ly/q8GifF