Well, we spent loads of time looking at this issue, but it was quite some time ago now which means I can’t remember the full results of our investigations. And a few pints of lager don’t help the cause either… The issue caused us so many headaches it was untrue. These were the exact issues you describe above, e.g. being able to calculate profit reasonably accurately so you can check it when you create a sales order. If I remember correctly we found that the unit cost was updated to be the same as the average cost when we ran the adjust cost routine. So, we made a small change to automatically run the adjust cost routine after posting a sales or a purchase invoice. This obviously took ages to complete so we then made a further enhancement to only run it for those items that were actually on the order which now means it takes a second or two. We then did the same thing for item journals and now we are pretty confident that our unit cost will always be the same as our average cost. If you ask me though, something is seriously wrong here and it is a definate bug unless my understanding of the inventory costing is completely wrong. Sorry I can’t actually give you a more helpful answer because we never got to the bottom of it. BTW, did you try it hotfix 9 on 3.70, this did some weird things on the costing as well and as we are now happy with what our system is doing we decided not to implement it.