Perhaps this will get rid of the leftover VM files from a clean OS install. Even root can't kill them, as the system thinks they are always in use. Command line has similar results. Apple should design an installer that cleans up after itself after clean installing.
There has been an app around for quite some time that does this. it's called "Force Delete" - I know the guy who made it. I think Force Delete is just a droplet, but it might have an interface.