I'm experiencing a strange issue here where the price navigation filter (layered navigation) somehow came up with negative price ranges.
If I flush the price tables it seems to solve the problem, until next time prices get re-indexed. Then the negative price ranges re-appear.
Another issue is that the price ranges are not even accurate. It would show the following: CA$0.00 - CA$9.99 (2) - as if there are 2 items within this price range. But we do not have any items priced within this price range...