Private Sub ListBox1_DrawItem(ByVal sender As Object, ByVal e As _
  System.Windows.Forms.DrawItemEventArgs) Handles ListBox1.DrawItem
 
Dim lb As ListBox = CType(sender, ListBox)
Dim dataItem As String = CType(lb.Items(e.Index), DataRowView)( _
  lb.DisplayMember).ToString 'hier knallt es
 
e.DrawBackground()
 
Dim I As Integer
Dim DR As DataRow
For I = 0 To GSMDataSet.Table.Rows.Count
   DR = GSMDataSet.Tables(0).Rows(e.Index)
    If DR("A_ID").ToString.Contains(dataItem) Then
       If DR("Ready").ToString = "True" Then
            e.Graphics.DrawString(dataItem, lb.Font, Brushes.Gray, e.Bounds)
        Else
            e.Graphics.DrawString(dataItem, lb.Font, Brushes.Black, e.Bounds)
        End If
    End If
Next

Gruß
Christoph