Oh, and how in the heck does a coin have a negative BTC value? If the exchange rate is so bad that the feeds exceed the value then I hope their engine would just leave it unconverted until there was a positive value.
Thats a bit odd. For a number of the stats we use floats (since most of the time approximates are fine) and there might be a rounding error. Can you post the address you're looking at and I'll check it out?
Isn't this from when blocks confirm but are later orphaned, or orphaned blocks are missed? It isn't a negative exchange rate, it's a negative coin balance because coins were paid out but later orphaned. No?