I just ran a scan with this free online scanner. It only works with IE in case you are trying to use it with another browser. I did a google search for "TrendMicro Housecall" and selected the first link to the free scanner and it worked without a problem. Make sure you are connecting to the correct web site and using IE. If that is true, can you provide a link to the web site? Do you know what "Web site is not authorized" is referring to? Are you trying to run through a corporate connection?
Have been using Trend Micro HouseCall successfully for several months. When I try to use it now this message shows. "Unable to run HouseCall because this website not authorised to host HouseCall" Does anyone know whats happening please ?