Duplicates-to id when occurs in 3 columns for unique dup in 4th co

[rking]

Need to identify when duplicates occur in columns 1, 2, 3 (each having unique
data that can reoccur numerous times), but only need when this occurs for a
unique duplicate in a 4th column. Using MS 2007. File is 6,000 + lines. Ex.
below with astericks is the only match I need to id. Thanks!

Column A Column B Column C Column D
123 20 Item1 053009 *
456 30 Item1 053009
789 40 Item1 052709
123 20 Item1 053009 *
789 40 Item2 052809
456 30 Item2 052809
456 30 Item2 052609

 

[Dave Peterson]

I would add a couple of helper columns and fill them with formulas:

Say in E1
=a1&"..."&b1&"..."&c1
(the dots are there to make the concatenated string unique).
and fill down as many rows as you want

Then in F1
=if(countif(e:e,e1)=1,"","*")
and fill down as many rows as you want