I'm having this issue now with 1.2.18. I was having it under 1.2.16, but the updated hook.dll fixed it. I haven't installed any new mods. I was getting CTD every couple hours with and old setup, so I reinstalled STEP Extended from scratch and now I'm having this problem. I'm 100% possitive I have 32-bit java BTW (just removed & reinstalled to be sure). Any help would be greatly appreciated. EDIT: After wasting the past 12 hours on this, I finally removed my head from my ass and activated SUM in the right hand pane and it's all sorted out.