screen goes black or is hypersensitive

I usually find the screen suddenly go black many, many times a day. often the screen is hypersensitive and there are sites I can't go to either because the screen will not stay in one spot so I can use it or read it or the screen blacks out every few seconds. after this I have to reenter all the info to get back to the site I was on. what do I do before I give up on computers entirely?