I figured this might assist some, so here are my findings: Recently I found that each time I pick up an air intake (stock or mod e.g. B9), the creator will go completely nuts, not allowing to click any button in game and eventually forcing me to shut down the client. I asked about it somewhere else, and somone suggested either TweakScale or KSP Interstellar as the source. As Tweakscale itself acted rather odd lately, I launched the client once without it. Problem absolutely solved. Since i'm not the type to delve in the configs or spend hours finding a costly solution, a simple removal of the mod will fix it all. Unfortunate, says my 7m diameter Energia replica.