Menu continuously flashing on sceen. Monitor Dell E77C menu buttons appears not to work. Can not exit and STAY exited from monitor menu. Computer Device Manager says no problem with Monitor, and troubleshoot with Divice Manger finds no problem. WindowsXP Version 2002 Home, Service Pak 3, Pentium 4 processor, Dimension 2400 series, factory install - order received Apr 2004.Have removed plugs from power & computer, reconnected, and tightened down; tried different power source. NO luck