Game often crashing when attempting to save duplications to creations tab

[CastrolGTX]

I've gotten a few complicated things with all sorts of wiremod things attached to save successfully, on and off multiplayer, but hitting the save dupe button is like rolling the dice. Sometimes it works, and sometimes it wipes out this crazy thing I spent 30+ minutes making and disconnects me from servers. I've got Win7 x64bit in case that matters. Does anyone know anything that can help?