User blog comment:Monkus142/Inventory loss/@comment-5196483-20120614174104

Well, I have one guess. Back sometime around Beta 1.7/1.8, there was a Dupe glitch in Vanilla Minecraft. If you dropped an item on the ground, hit save an exit, came back into the world, picked up the item, waited ten seconds, then X-d out of Minecraft, came back in again, the items would still be there. I am guessing that in an effort to fix this (The bug was fixed, I am just guessing on how it was fixed) Mojang changed the code so that it doesn't autosave the inventory. I am guessing that when you went to the nether, there was a huge lag spike, causing the game to freeze. When you X-d out, the game would have reverted your inventory to the last save, but kept your position the same. If your last save happened when you had nothing in your inventory, that would've caused the lack of an inventory upon return.

-Sorry for the long post, but it should be logical.