I was running a modified mindcrack with traincraft removed, and mo creatures, thaumcraft, and twilight forest added. Because of mo creatures spawning mechanics, I was overpopulated with angry zombies. Almost every single one. ugh. So despite liking mo creatures, the angry zombies were just too much. When I upgraded to 1.4.7, I removed mo creatures, and started a new world. Really digging GT and all the uses for many items that would have been recycler fodder before..