Malware has infected my user’s computer. As administrator, I am unable to disable System Restore, or modify the corrupted HOSTS table, or access the USERS table. Per the Events Viewer and entry in Symantec log, the malware may be Downloader.MisleadAPP or Trojan.ByteVerify or something else. How can I regain control of this PC aside from re-formatting and re-installing Windows?