keyboard problems

I have a HP zt1150 laptop computer and i am running windows xp professional on it. The problem i’m having is that certain keys occasionally dont work. It is mainly certain vowels and things like the directional keys and the delete keys. Some people have said it is the keyboard but i beleive its some type of virus, as when i type at times it works then after a while those certain keys will stop working its like after i type a letter someone just hit the backspace key and deleted the last letter.