I placed the Air Marker in a building in my world and let it running. There were some holes which resulted in the entire chunk being filled with the Red Blocks. This lead to a crash that continues to happen on world entering.

Forge 1307
Modlist

EDIT: Disabled Fastcraft, Optifine and Shaders. Not it does not crash anymore..

Bugger. Sorry @Yulife, the puush expired so I don't have a copy of the crash log anymore, I'll have to close this bug unless you happen to still have the world and can reproduce the log.

Hehe, I added an EDIT. It was Optifine :)