suddenly my laptop screen has gone blank, though i could hear the windows program opening up. i connected to an external monitor and saw the text and images correctly and from my laptop typing screen. i could use the laptop keyboard again efficiently.I went to appearances and changing the settings did not work.i enlisted the support of an I.T. specialist but he gave up.Also sometimes the resolution goes to its 600x ? settings and will not allow a change but then it does after rebooting.Is this a hardware or software problem ?