Laptop keyboard malfunctioning?

-when i click to write something, loads of p's appear, as if i were holding the p key down. for a while, i couldn't actually use the p key, so i'm assuming it's not caused by pressure. it works again now though. i also took the button off ( they can just click back on). could this be a virus? i scanned my system with avast but it said nothing was found. please help! thanks for reading