My Ps3 Controller Does Stuff on Its Own on Black Ops?

when i play black ops or mw3 my controller will switch to my secondary weapon, crouch even jump on its own but it doesn't do it all the time i tried it on my brothers ps3 never would do it on his system how do i fix this

Same happened to me. No way to fix it. You should buy a cheap one like the Gioteck HF2. I have it, it's good.