When Forestry is installed you can get bees with hidden data. try and sort a chest with them in it, and you get a massive infinite loop which crashes the server, and the only error message is a huge pile of

2014-01-25 16:14:27 [WARNING] [Minecraft-Server] Memory connection overburdened; after processing 2500 packets, we still have 11354328 to go!

That number rises every second, until RAM runs out and the server dies.

This is not a crash (just things getting slow), and is probably a duplicate of #103.