Eddy
7
“move to chest” moves the files to a special folder within the Avast folder. Avast protects that folder so the system doesn’t access the files there. This will make sure the infected files won’t do harm. While in the chest, you can anlyze them further to see if they are really infected (need to be deleted) or not. If it is safe to delete them, you can do it from there. If it for whatever reason turns out that a file is falsly detected as infected, you can place it back to it’s original location from there.
For HijackThis, look HERE
Files in the winnt folder doesn’t mean they are system files. Many virusses place one or more files there as well do legitimate applications.