Dim oldRow As Long
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Application.ScreenUpdating = False
If Not Intersect([C2:S18], Target) Is Nothing And Target.Count = 1 Then
Target = Array("X", "")(Abs(Target = "X")): [A1].Select
Cells(oldRow, 1).EntireRow.BorderAround LineStyle:=1, ColorIndex:=1, Weight:=1
End If
If Target.Column = 1 Then
If oldRow > 0 Then Cells(oldRow, 1).EntireRow.BorderAround LineStyle:=xlContinuous, ColorIndex:=1, Weight:=1
Target.EntireRow.BorderAround LineStyle:=xlContinuous, ColorIndex:=3, Weight:=xlThick: oldRow = Target.Row
End If
End Sub