It thinks there's activity. I've never been able to figure out why, on the perhaps
one in ten laptops the condition develops in. If it's a LED display, it won't
matter; but a flourescent light screen will die after a few years when the bulb
fails.
You can turn it off (if the laptop has to remain on) by selecting do nothing when I
close the laptop lid, wherever that option is on your system; and close the lid far
enough to trigger the switch that shuts the light off.
You can turn the monitor off with a program if you have a C compiler
#include windows.h
main() {
sleep(1);
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2);
exit(0);
}
but if it's discovering activity it may (or may not) turn itself back on soon.
--
On the internet, nobody knows you're a jerk.