chbg has nothing to do with screensavers but with background settings.
For the screen blanking, it may be due to the graphic card. Do you have direct rendering enabled ? If you don't know, you may have to install mesa-demos, then in a console, as user is ok, type "glxinfo | grep rendering".
Knowing what your Graphic card, at this point, could also be useful. You can type as root: "lspci | grep VGA".