XL Macro Crashes on one PC only. Automation error the object invoked has disconnected from its clients

I've seen cases where it helps to insert an Application.Calculate between lines 9 and 10. ALternatively, a DoEvents at the same point might also help.
As a side note, this SUMPRODUCT formula can be efficiently replaced with a SUMIFS formula:

ActiveCell.Formula = "=SUMIFS(OrderBook!$K$2:$K$" & lngOrderBookLastRow & _
    ",OrderBook!$B$2:$B$" & lngOrderBookLastRow & ",Master!$A3,OrderBook!$N$2:$N$" & lngOrderBookLastRow _
    & ","">0"",OrderBook!$N$2:$N$" & lngOrderBookLastRow & ",""<=""&$B3)"

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HKFuey

It's not in the spirit of any help forum to delete the question and not share the solution. Very poor forum etiquette!