The code below will place a 'True' in the next column to any cell containing comments on the activesheet, you could then use Autofilter on that column to only show those rows which contain comments. Note that this will overwrite cells you may need, if you have comments in any other cell other than those in column D. Please repost if this is a problem and we'll see if there's a solution:-
Public Sub FindComments()
Dim c As Comment
Application.ScreenUpdating = False
For Each c In ActiveSheet.Comments
c.Parent.Offset(0, 1).Value = "True"
Application.ScreenUpdating = True