online file backup won't exclude system files

Trying to do a cloud backup of only data files on a Win7 laptop. In the users' folders (C:\Users\username\) only the Desktop, Favorites, Links, My Documents, My Pictures, My Videos folders are checked. However, system files and folders are being backed up, i.e. NTUSER.dat, AppData folder, etc. The Exclusions tab lists System Volume Information and the "Files matching the following criteria" box is checked. The Hidden Files and System Files checkboxes are grayed out and won't let me select them.

Curiously, on a similarly configured desktop, system files and folders are NOT being backed up.

What am I doing wrong?