Monitor Problem

I am using a Micron sytem with a 17 Micron Monitor. Recently when I booted my sytem I noticed that the screen display began to expand horizontally pushing the screen Icons off the page. When I run other applications the screen size is constantly changing expanding and contracting both horizontally and vertically. I can use the monitor controls to adjust the display for any one application, but it will not be correct for other programs. I have reinstalled my drivers for my video card and monitor, but this has not helped. I have also checked for any viruses and I am clean. Is this a hardware or software problem? Any suggestions.