I am having this issue also with a home computer and the latest updated McAfee anti-virus product. This trojan keeps popping up alerts stating that the computer is infected and wanting me to click to purchase their fake av product. It also blocks Malware bytes anti-malware from running. I am receiving emails for additions to this thread and hope someone at McAfee can help. I believe the actual name is "Antivirus XP 2010".
Have a look here
Some people have had good success with this tool, other less so. As a first run you might want to run it in report only mode, with network heuristic check sensitivity level set to high (both available on the 'preferences' button - and please don't run one without the other). Once it's complete please post the report file up here and we'll take a look for you.