Robin van der Noord

It doesn't give a crash rapport, minecraft just freezes forever and I have to force quit it

O I'm sorry

And the stripped version (doesn't work either :s):
/summon Zombie ~ ~1 ~ {CanPickupLoot:true}

/summon Zombie ~ ~1 ~ {CustomName:Clone,CustomNameVisible:1,Attributes:[{Name:generic.movementSpeed,Base:0.01}],CanPickupLoot:true,isBaby:1}