LCD monitor display issue

Hi there.  I think this is a monitor problem vs. computer problem, but I could be wrong.  I have a Mac computer and use a Samsung  SyncMaster 570V LCD monitor.  The monitor is pretty old (8 years or so).  Just recently the screen changed so for example, when on a website, the normal white background is black, and normally the print that was black, is white.  It is almost "reversed" in color.  So photos are impossible to recognize, because peoples' faces are "white out".  Hopefully this makes sense.  I can't figure it out by playing around on the computer because I am not good with computers    Any help would be greatly appreciated.  Thanks in advance!!