I have a Inspiron 570 that came bundled with a Dell ST2320L monitor and an ATI Radeon HD 4200 video card with driver 8.850.0.0 which is current.  Up to now the entire width of the monitor was being used with no distortion.  I downloaded and installed some recommended drivers from Microsoft and now the display is only using the right 75% of the monitor with a large black bar on the left.  How do I get my full width display back?