Game crashes when placing a Molecular Assembler or any of the Crafting Storage blocks at y = 0. The block must then be removed before that chunk can load with out crashing. Would guess they are looking for blocks to connect to at y = -1.
AE2 rv1 beta 37
Crash Report: http://pastebin.com/68GF6mwQ
So don't place the block there?
How are you even hitting this? Creative?
Yeah creative. When experimenting with a mod I like to create what amounts to a void world so my laptop doesn't have to render more than it needs to. I tend to like building ridiculous setups that make placing a block in the chunk the setup is in cause something like half a second to a second of lag as it rerenders the chunk.