If MB is find and removing the virused then may be it can block then from reappearing. The free version do nothe prevent attacks. Install the full trail version, hopefully this will staop the viruses from reappearing. Your main anti-virus program may have disabled by the viruses, that why they keep reappearing. After installing and running the full version of MB, restart in safe mode and reinstall your main virus program. Hopefully there's no conflict between the program, if so turn of MB and then reinstall your virus program. There may be a program thats allowing these viruses to come back throught a back door. Uninstall or diable programs that you don't use or did not install, also torrent programs like bearshare. Install browser toolbars. There are other steps to take but try these simple steps first.
If you have futher issues you can contact us, we can help via remote support.