I've been having this issue lately where the precaching just stops randomly and all the item thumbnails disappear, making it impossible to select anything. If I hover the mouse over an item, the title still shows up. If I click on it, the mouse turns into a "you can't click on anything right now" symbol, but I can still save and leave. If I try to place an item down, it says, "item loading."
Once I close the game, I try to restart it and the computer asks me, "are you sure you want to allow this application to make changes?" I click, "yes," but the game window never shows up, however Task Manager says that it's still running. The only way to solve this is to restart the computer.