With CCL / CCC installed, can't tell which one, if a mod has a missing mods exception, the forge GUI that would normally display, does not display and instead, the game crashes.

For example, if I installed RFTools without McJty Lib, forge would stop loading MC and prompt me that I am missing the McJty Lib. With CCL installed, this GUI doe not show.

http://pastebin.com/5Am1MQC1

The GUI acts as normal after removing CCL and CCC. (Plus EnderStorage, ChickenChunks and NEI)

Interesting, ill look in to this.

do you have JEI installed for NEI?

Yeah, the missing mod was 'ZeroCore' for extreme reactors

Version 2.2.3.72 of CCL appears to have fixed this problem. I'll update this if it happens again!