Game either crashes or is on an infinite "importing" screen

So the bug has happened before not the first time but I digress. The bug is when you try to download a texture pack/resource pack the game will download it and the game will Crash, install it, or just infinitely say, "Importing". Nine times out of ten it just says "Importing". Oh and "Mashup packs" have no data. What I mean by that is there's nothing to install 0/0 Kb.