If it keeps doing it with other internal connected keyboard then it's a motherboard fault.
I can't be sure what you meant by "pluged in other one." That is, if you plugged in some USB keyboard, then there's a little hope. Unplug the internal keyboard and retry.
I have a problem with a keyboard in my dell laptop.
"P" key appears to be stuck - as it is constantly pressed.
I know its not a keyboard issue, because i pluged in other one and the problem remained. Also its not a software issue, because im have two operating systems and its the same on both of them.
What might it be?