The previous versions of LotsOMobs all have had the same problem, they crash when installed together with other mods that add a lot of entities. I was unaware of the fact that there was a fix for this untill I got some messages about it a few days ago!
This has now been fixed, and LotsOMobs should again be compatible with all other mods! With the help from: http://www.jabelarminecraft.blogspot.no/p/creating-custom-entities.html everything has been made perfectly!
This update also contains changes to the spawn eggs. The new registry doesn't support the vanilla spawn eggs, therefor I made custom ones. They can be found in the LotsOMobs Spawn Egg tab. They even have a new design!
So have a lot of fun
AND PLEASE MAKE A BACKUP OF YOUR WORLD BEFORE PLAYING!