I have recently changed my motherboard and reinstalled the operating system (Windows XP). All seemed well. However, during my loading of Microsoft Office, the screen turned itself off (I don't think I touched anything). When I turned it on again, I found that the displayed
image had become much smaller than the monitor's screen area. I now have a 1.5 inch black margin on both sides of the display.
Referring to the Catalyst Control Centre, I have tried to correct things by adjusting the desktop area, but there is no response and the setting remains stuck on 1440x900 (which incidentally is the recommended setting for the screen)
The screen has worked perfectly for 4 years, so what has gone wrong now? Help please.

Referring to the Catalyst Control Centre, I have tried to correct things by adjusting the desktop area, but there is no response and the setting remains stuck on 1440x900 (which incidentally is the recommended setting for the screen)
The screen has worked perfectly for 4 years, so what has gone wrong now? Help please.