shift key randomly held down internally, seriously affecting performance

SomeHOW IT SEEMS THAT MY SHIFT KEY RANDOMLY (YES THIS IS THE REASON FOR ALL OF THE CAPS) GETS HELD DOWN_ you don't really realize how much this affects you unTil you try operating this way. I OFTEN CAN't sign in to things because i can't properly type my user names or passwords because i can't use both upper and lower case and i can't use numbers. When i surf the web, all links open in new windows and it causes a lot of lag on my computer in general. This is getting realllly annoying at this point, does anyone have any idea of what Might be causing this? I NEED IT fixed  asap. THANK YOU>