Try adding the remaining selected attributes to your group by clause. So it would go something like this.
Select distinct
labor.Dept AS DEPT,
labor.Job AS MS,
countsheet.PART_NUMBER,
Sum(labor.Total) AS DEPT_HOURS,
countsheet.TOTAL AS TOTAL_QTY,
countsheet.DUE AS UNCOMP_QTY,
countsheet.NET AS COMP_QTY
From
labor,countsheet
Where
labor.Job = countsheet.MS
Group By
labor.Job,
labor.Dept,
countsheet.PART_NUMBER,
countsheet.TOTAL ,
countsheet.DUE ,
countsheet.NET
Order By
countsheet.MS Asc
;
Oh, and I'm not seeing where countsheet.MS is being selected. Using an attrute in an Order By cluase that hasn't been selected may cause unexpected results.