Sudden acceleration during reentry

[strigon]

So, I was coming back from a Kerbin orbit, and things were going well. Heat was well in hand, and I was slowing down nicely.

Suddenly, I started slowing down much faster; I thought it was peculiar, but I attributed it to being lower into the atmosphere leading to increased drag. Then, when I reached a velocity of 1,500 m/s, I started accelerating again. Not gently, as though air resistance was gone, but quite forcefully; the G-meter maxxed out, and in a matter of seconds I was back up to orbital velocity, and my ship exploded from the heat. The ship in question, at the time, was just a Stayputnik, a couple of goo canisters, batteries, parachutes and thermometers, with a mat bay and heat shield slapped on the bottom, and micro legs for landing, if it matters.

To reiterate; during reentry I started accelerating toward the ground at 10+ G's. This wasn't my craft being too heavy for a gentle reentry, it was the almighty hand of God slapping me down toward the planet's surface.

[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?

[bewing]

That sounds like this issue: http://bugs.kerbalspaceprogram.com/issues/8974

The other players who saw it seemed to be experiencing upward forces, rather than downward. It's a rare enough bug that the devs might be having trouble tracking it down. I don't know. You may want to add your savegame to that bug report.