I wonder if the group by's are causing some sort of problem. Have you tried dumping them to see if it produces correct results when doing whole table (or at least your entire 'where' selection)?

Alan

>More info.
>
>I have been able to reproduce this behavior with more generic tables.
>
>I have also discovered that I can include the same SUM() calculation at the top and bottom of the select. The one at the top is correct the on at the bottom is incorrect.