when i start 'screen' from an xfce4-terminal, the 'backspace' key doesn't work.
the fix is to use the Edit->Preferences... menu item in xfce4-terminal, go to the "Advanced" tab, and change "Backspace key generates:' from Auto-detect (the default) to either ASCII DEL or Control-H.
This post indicates that screen has this problem with some other terminal programs have this problem, too.