One thing has just struck me.....
I see your ram is at ddr800, Im guessing that the cpu is at stock and youre using the divider to up the ram? If so, this could well be the problem, and my board also has similar problems to you when I use certain dividers at certain a fsb. If you can set it to 1:1 and try orthos again.
I'm having a similar problem to you with ram dividers, but I didnt realise that you were using one, thats why I havent mentioned it. DOH.
Let me know how you get on with 1:1 :)