The issue is outlined over here: BluSunrize/ImmersiveEngineering#1652

Basically, the game crashes and then hangs on the loading world screen after trying to enter a SSP world. Blu mentioned the issue is to do with a null EntityRenderer, and someone else pointed out your latest changes to CCL may be the cause of this.

Crash report: http://pastebin.com/zMUd21T1

More details in the IE issue.