If you have cheats on and you give yourself a mob spawner and then a blank spawn egg (without making it any specific mob) and try to set the spawner with the blank spawn egg the game (for the game's host) crashes. I haven't made any modifications and I use 1.8.1 on Windows 7. I see this in Creative and Survival.
/give PLAYERNAME mob_spawner
/give PLAYERNAME spawn_egg
Place mob spawner and pull out spawn egg and try to set spawner with it.
Mob Spawner Crashes Game