Hello - when changing pages on a website, or going from one site to another the screen on my pc blanks, and the led goes from green to amber - standby mode. After 20 or 30 seconds the led again goes green and the selected page appears.It doesn't happen every time, though. OS is Windows xp professional, graphics card an NVidia GE force MX 200, motherboard Elite K7S5A. System was built circa 2001. Suggestions gratefully received. I will probably be able to try a new monitor, but not until next week, unfortunately.