Everything refuses to load

Materials, scripts, everything; they all refuse to load when I try to load them… this is INADEQUATE! Help!

Does this happen for all of your projects or just one specific project?
Does it happen for projects not created/owned by you?
Do your scenes fail to load in the Editor? Or do scenes load fine in the Editor but fail to load when you hit Launch?
Can you link to a project that highlights the problem?

Please do provide as much information as possible when reporting problems.