How can I remove Troj/Iframe-HJ?

I installed Sophos Anti-Virus 8.0.6C for Mac today.  It almost immediately found Troj/Iframe-HJ.  However, when I go to the Quarantine Manager, put in my admin password, and press Clean Up Threat, it says "Cleaning up threats..." but the task never finishes.  Is there another way, or another version, I should be using?  And can anyone tell me anything else about this threat?The Sophos website, http://www.sophos.com/en-us/threat-center/threat-analyses/viruses-and-spyware/Troj~Iframe-HJ/detailed-analysis.aspx  is kind of obscure.

Thanks.

JK