Like I say, no error message. It just sits there and tries to load a page, waiting and waiting, with no progress on load. After about 2 seconds I'll hit refresh, and it will do the same thing. Then about another 5 or 6 secs later, I'll hit refresh again and it will work just fine, as if nothing ever happened.
So maybe I'm getting twitchy and don't give it time to throw an error message at me. Next time it happens, I'll just leave it alone and see what I get.