Keys Get randomly Pressed(number 4 & 5) and Mouse becomes Unresponsive

This is not aprogramming question but I have posted it here as I have not got any specific answers.My PC suddenly Displays 4 & 5(below F3 AND F4)being pressed and also mouse becomes unresponsive.I also turned the sicky key setting to off state but still it doesnt work.I Have been using External Keyboard(I dont use the built in laptop keyboard since the time I bought it).Please help. Thanks In Advance.