We have all experienced our fair share of crashes caused by voxelmaps and custom mobs. There has been a fix out for that issue for quite some time, but it is confusing as VoxelMaps, and Zan's minimap are the same thing, but recently changed names. I removed voxelmaps and just plopped in zan's from here: http://www.planetminecraft.com/mod/zans-minimap/ It was a direct replacement, and it even saved all of my waypoints/settings as well. I tested the latest 1.6.4 version and there are indeed no more crashes from the minimap when custom mobs are displayed.
