In addition to "uninstalling" from "Add/Remove
Programs" ( I had to uninstall 3 "components" ) and
running the SymNRT "tool", you should use your machine's
"Search > All files and folders", entering the Search "term"
"Symantec" and later on "Norton" and try to "Delete" all
appropiate items that are listed. Then, if possible, use a
SAFE "registry cleaner" to remove additional items. Then
your machine would be rid of Norton, allowing a complete
installation of Avast .