Inventory and items in all chests dissapear when switching from 14w06b to 1.7.4

When I switch from snapshot 14w06b to full 1.7.4 version all of the items in my inventory, even armor, and any and ALL chests in my world disappear.

What I expected to happen was to log in and still have my inventory

Also I tried to get the info in the Development console, hoping it'd help, but only the first step could I get it, after that the launcher was either so slow it couldn't keep up and I couldn't copy and paste, or it just froze, it didn't move around when using the scroll bar the .png I attached is where it froze and I could get a shot of it.

Steps to Reproduce:
1. Log into a regular 1.7.4 world with items in inventory, chest, or both
2. Reload world with 14w06b
3. Load yet again with 1.7.4
4. Look at inventory