Clearing Constant Cells

[The Animal]

Hi
I have the below to 'Clear" the cell data but ignoring cells with formula from cells A4:Z10000. It work fine when you run the macro once (when cells have data) but if you try to run again then hangs up on below "Selection Line" (in red below). If you then add any data at all in a cell anywhere from A4:Z10000 it will then run OK. How would it look if I want to run macro again without having to add any data.
Thanks for any help Stephen

Sub ClearConstantsA4toZ10000()
If MsgBox("Are you ABSOLUTLY sure? (1) This action will DELETE all Data from Row 4 to 10000 THIS ACTION CANNOT BE UNDONE", vbYesNoCancel) = vbYes Then
ActiveSheet.Unprotect
Range("A4:Z10000").Select
Selection.SpecialCells(xlCellTypeConstants, 23).Select
Selection.ClearContents
ActiveSheet.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True _
, AllowFormattingCells:=True, AllowInsertingColumns:=True, _
AllowInsertingRows:=True, AllowFiltering:=True

End If
End Sub

 

[MARK858]

What happens if you remove all those selects and put in error handling i.e.

Sub ClearConstantsA4toZ10000()
    If MsgBox("Are you ABSOLUTLY sure? (1) This action will DELETE all Data from Row 4 to 10000 THIS ACTION CANNOT BE UNDONE", vbYesNoCancel) = vbYes Then
        ActiveSheet.Unprotect
        On Error Resume Next
        Range("A4:Z10000").SpecialCells(xlCellTypeConstants, 23).ClearContents
        On Error GoTo 0
        ActiveSheet.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True _
                                                                             , AllowFormattingCells:=True, AllowInsertingColumns:=True, _
                            AllowInsertingRows:=True, AllowFiltering:=True

    End If
End Sub