heyyou

Ok. Three or four years ago, my HP ze5300 randomly started acting up. It wouldn't start etc, blue screen of death & so on. We took it to a repair guy. He was as lost as us. So we stored it in the attic. Well a month ago, I got it out. Low & behold, it runs okay now. I found a lot of viruses and adware on it so I whipped the OS. Well now it runs perfectly.. except for the fact that sometimes when you turn it on, the screen stays blank but the fan runs and the lights come on too. Othertimes, this terrible screeching noise starts going off when I rest my hand beside the touchpad. The battery doesn't charge either..and the blue screen of death comes up (rarely though ). So..honestly I have NO idea what's wrong with it. Could it be the power supply? Or the motherboard? or what? I'm lost.