My sister's PC has the paid version of PrevX. My brother went to some tourism Web site and clicked on a picture. Lo and behold, malware took over the machine. It was one of those fake "your machine is infected" things, along with references to a spambot that sends out e-mails. I managed to stop a couple of processes (start.exe was one, I forget the other.) One of the many symptoms was a large gay porn picture on the desktop! Anyway, I am going to attempt to clean this up. I might download Combofix, which has saved me on more than one occasion. What concerns me is that we ran a PrevX scan, and it found nothing. This surprised me, as I've had good results with PrevX thus far.