ModPack: Monster v 1.1.1 + GregTech + Ars Magica 2 - RotaryCraft and all it's addons, server is on Cauldron 1.6.4
Mod & Version: it's likely to be Factorization 0.8.34, but I'm not sure
Pastebin link to crash log: http://pastebin.com/R5K31pzC
If you need error report log from Java, it's attached...