More info... No Problem! So this started happening in ksp 1.1.2 (the newest update). For eksample: i launch a rocket with 3 stages. On the two first stages the sas is working fine and i guess its because the rocket is pretty big at that point, but when i use my last stage (when the ship is smallest and has a light weight and its in space) using my sas is useles. When i activate sas my ship shakes (does not explode). When targeting a node my ship slowly rotates towards the node while shaking and then it overshoots the node and for some reason does not target that node anymore, it just shakes. It also happens on reentry with a planet with a atmosphere, something that makes me unnable to stabilise my capsule so that the heat shield points downwards and i cant make a sucsessfull reentry . The yaw, pitch and roll bars on the botom left corner moves randomly up and down, left and right. If i have rcs thrusters on my rocket they fire in random directions when activated.
(im playing the stock game without any mods and i really need help)