Default scheme not loading, then models/error.mdl couldn't be loaded

What is happening is, when I start Hammer using the SDK, everything is fine.
When I go to load a map, first I get the “Failed to load the default scheme file. The map views may be missing some visual elements.”
I click ok and it starts reading chunks for about half a second, then I get “Model <name of a model> not found and models/error.mdl couldn’t be loaded” (<name of model> varies on the map)
This happened all of a sudden, I literally used it 30 minutes before. I closed it, ate dinner, then got back on, but got this. All this happened 10/24/13
I’ve tried re-configuring, I’ve uninstalled and reinstalled, restarted my computer. I need Hammer :frowning: can’t do anything without my baby <3 lol

Anything other info you need I’ll add here:

Thanks! :3