One possibility is that the settings in WINDOWS EXPLORER are not set to view HIDDEN or SYSTEM files; need to go to the FOLDER OPTIONS under the TOOLS Tab for that. Another may have something to do with not having ADMINISTRATOR rights to view the contents of the entire computer. Otherwise, it may have mutated into another .EXE as I've read elsewhere. Perhaps you can search for other .EXEs with roughly the same Time & Date Stamp as the onset of infection...?