Can't go into Minecraft world.

Minecraft loads just fine, if taking quite a while. I can then look around at the new skin thing and everything else. However, when I go into a world, after generating the world for a bit, MC crashes.

Edit: It works if I create a new world or go into another world without resource packs.

Okay, ignore all that. Instead of displaying a 'resource pack not compatible' message, minecraft just crashes.