Does that entry show up for all objects (drives, folders, files of any type) or just for particular file types? If it shows for all objects, check the registry below
HKEY_CLASSES_ROOT\*, particularly the
shellex subkeys. Try deleting the
- Start regedit (as administrator) and navgate to
File > Export... and save the key to a file.
- Delete the key.
X64 entry still appear after that? Re-import the registry file you saved before to undo the change.
You could also try a registry search for
X64 (whole string in keys and data):
I don't think it's very likely that you'll find it that way, but it won't hurt to try. You need to look only below
HKEY_CLASSES_ROOT. You can stop the search when it hits
ShellExView: an extension won't necessarily be registered with the same name that is displayed in the context menu. Start the program (as administrator) and order the extensions by company (it's unlikely to be a Microsoft extension, so you probably should focus on the non-Microsoft ones). Which non-MS extensions are listed there? Ignore the ones that you can clearly identify and disable the others.
Does that remove the context menu entry? If so: re-enable half of the disabled extensions. If the entry re-appears it's among that half, so disable half of those extensions again. Otherwise it's among the other half that's still disabled, so enable half of those extensions. Continue until you have narrowed down the problematic extension.