So, I got the Aether II mod to work on my UMS modpack, and it works perfectly up until the point that I actually go into the Aether portal, at which point it says "shutting down internal server". I got this crash report:
---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.
Time: 9/12/14 8:21 AM
Description: Exception in world tick
*snip*
How should I go about fixing this?