Konrad-Brabus

I have almost the same problem, my space plane starts accelerating during reentry when i hit 68km and if the angle is too steep the ship will explode due to heating, also, the ship starts tumbling without control as soon as the bug kicks in, the more i try to control it, the more it tumbles, and the more it tumbles and moves around crazily the more acceleration is experienced, i reached 6800m/s once before exploding at 65km from Kerbin's surface... Sooo what is going on? How to fix this?