His dllhost.exe isn't a system file though, since he told us where it is, and that's the location the nachi "virus" puts it's own dllhost.exe (as I found out after I bothered reading what the virus is about, unlike someone in here that should have done ) - the real one is in the system32 folder and not a subfolder of it.

As Bley's said, delete it (Not the real one, the one you said was detected as a virus )