it was totaly ok from last 4 years. i had antivirus avast from internet for free. when i start my laptop, so it was fine, it asked to renew the antivirus and asked for this i should restart my laptop so i clicked on yes button. and after that it starts but nothing i can see in the screen. some time it takes long time after puting my password, when welcom comes so it takes som minuts and after that nothing in the screen. totaly black. just i can move the mouse. please help me what to do?