Nvhost.exe is a mass-mailing worm W32.Mytob.HM@mm. Nvhost.exe opens a back door on TCP port 6663. Nvhost.exe tries to terminate antiviral programs installed on a user computer. Related files: %System%\nvhost.exe Adds the value: "Messenger Service" = "nvhost.exe" to the Windows startup registry keys. More info: http://securityresponse.symantec.com/avc... Removal: Kill nvhost.exe process and remove nvhost.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.