I had mentioned this elsewhere but thought about officially posting here.
In certain circumstances Kratatmos will hang max when PRT FumeFX has unfilled prerequisite channels. ie no fuel = block at render time evaluation of atmospherics.
This will be fixed for the next beta build.
You sir deserve a thanks 
Could this be similar to why my Box 2 hangs from another post? Insuffienct channel data?
Most likely not related.