It appears that the Group By in version 6 has changed the way it works from pervious version.
In pervious version you could have two Group By statements separately and they would create a nested data table. Group By Field 1 - Group By Field 2 - Count.
In version 6 however that construct now double counts log records. You have to do Group By Field 1, Field 2 - Count. Then sort by Field 1.
Hopefully this makes sense. It was not obvious to us at first until we started comparing values on some tables to ones we had recorded.
Be aware in version 6 having two group by (or nested group by ) statements can double count your log records.