The Caps Lock on my Dell laptop comes on then it shuts down!?

My Caps Lock comes on then my laptop shuts down. I have no viruses or anything bad on my system according to my security stuff. Does anyone have any idea what is wrong. I have looked at previous questions and they say something about memory sticks but I am not using one so I don't think that's it. I am not brilliant with computers so could you keep your answers simple, think slow 7 year old and I might get it! Thanks in advance to anyone who tries to help