Hopefully this will help. It's a double whammy...
Because the server is reporting wrong khash and the payments have gone down, we (everyone seeing this issue) are actually losing 25% of what we're doing somewhere.... HUGE deal...
Considering the minimum hashrate over the period you are viewing was 0MH/s, you average number is not going to be correct either. Server isn't reporting the wrong KH/s anywhere I have seen.
That minimum could be only be for a few minutes... I too am suffering at around 03:00AM-04:00AM pacific time two rigs always freeze ever since update. Not sure is this is due to server resets and my rigs not being able to recover or just coincidence. I am sleeping at this hour so i dont find out till i wake up.