FB does a fast takedown
A researcher we know who prefers not to be named found this on the Zynga game Mafia Wars. When you shared it, you were offered a free gift if you completed a survey.
The free gift you got was an installation of MyWebSearch which Sunbelt detects as an potentially unwanted program:
“MyWebSearch Toolbar is a customizable Internet Explorer search toolbar with various other tools. These tools include a pop-up blocker, screensavers, and cursors. Searches entered into the toolbar search field are directed to MyWebSearch.com.”