we have a toshiba satelite 1800-400 running windows me. recently when being used the screen goes from windows display to a blank/black screen. when the small pin is pressed (at the top r/h side above keyboard panel) the display resumes to normal. all hibernate and sleep times are on max. the problem gets worse if the a/c is plugged in, then you have to keep pressing the small button to resume normal display, but imeadiately it wil go blank again. it has new battery. is this software or hardware?