Charwal

I really am not sure why, but whenever I tried to land on any planet/moon, my craft just falls apart and soars around, or just crashes into the ground. I have a video link here, skip to 3:00 for when the bug happens https://www.youtube.com/watch?v=arMBXbUpAog&feature=youtu.be i am running this on x64 bit ksp version 1.12