I thought this was some Easter egg or something, but apparently not. I tried it a few times to make sure it was actually happening. Funny thing is, I actually have this picture on my computer (that classic Macy's Windows error message). I guess somehow the Finder icon that should be there got tied to that? How the hell? Maybe I previewed it in the Finder and some graphics somehow got corrupt? Anyway, it was very weird. I logged out and back in, and now it's back to normal. Hmmph.