So I recently started playing modded MineCraft and I get the mod packs I use from twitch. I have been playing FTB Mage Quest and FTB Infinite now for a few weeks and am having a reoccurring issue with my worlds. I will create a world and play it for 5-7 days and then one day ill try to get into the world and it will crash every time I try to open it. This has happened twice on Infinite and once on Mage quest. I have tried restarting the game and my computer and nothing works. Does anybody know how to fix this problem so I can play on my worlds again?