This is also affecting 1.0.4 (Win 10, Realm)
I set up an enderman farm in the end, near Y=0 and about 200 blocks from the main island. I have yet to see an enderman spawn on the pad, but I've got plenty of creepers, zombies, and spiders.
Sorry for the multiple posts. I opened the file in an NBT editor. All of my armor had a damage of -26005 (IIRC). Editing it to 0 and running again allows me to play. I have no idea how it got to be that. Like I said, I was in the Nether. I've also noticed blazes occasionally doing way, way more damage than I think they should. As in, they normally do about 1/2 to 1 heart with my armor (diamond with protection, fire resistance) but twice I've gotten hit 1-2 times, then as I turn around to deal with it I'll just be dead. I'm in an area where no ghasts can spawn, and the game says I'm killed by a blaze. It could be a total red herring, but maybe there's something weird about their damage?
I also have this issue in a realm. I don't know if it has to do with blazes, but I was in the nether when it started. It appears to specifically have something to do with my armor, as I can look at everything else when, say, opening a chest or crafting table, but hitting e crashes. Figuring it was my armor, I tried drowning myself to fix it. I could open my inventory when I respawned with no equipment. When I went to get my stuff, my game crashed while I was trying to collect it.
I'll attach my save.
*edit I can't attach the save. It's 18MB, which is bigger than allowed. What/where can I upload?
This is not fixed. Please re-open.
I had it happen in 1.0.5. I was eagerly awaiting the update because of problems with this.
I went through the Nether to travel to a distant part of the overworld with another player in a realm, then came back. Upon returning to my base, all nearby peaceful mobs had despawned. This included sheep that I had bred, penned, and dyed with each available color, cows I had bred and penned, dogs that were parked, and a corralled, tame horse.
I'm not sure if it is the same bug, but I also had a cat despawn within a few seconds of my taming it.
If anything, the bug seems worse. I'd lost some chickens before, but in this case I lost every single domesticated animal in my base.