Unprotecting a cell

I Need some help understanding where to place the code to Protect and unprotect my worksheet. Each work book contains 5 buttoms and when one is clicked it unprotects the sheet before running the code, then re-protects the sheet. I had a circular reference error because of the way the formula was written. The problem I am encountering is when the cell that the new code references is selected I get an error saying "The cell or chart you are thrying to change is protected and therefore read-only" I can maually unprotect, then after the change is made the cell protects itself. I would like it to unprotect with out having to click on the unprotect button
 

Private Sub cmdRndOne_Click()
' Round One Macro (Main Ratchet Round - All except PreCall)
' Macro recorded 5/16/2008 by Mark Baird
'
' Keyboard Shortcut: Ctrl+r
'
    ActiveSheet.Unprotect
    Selection.AutoFilter Field:=5
    Selection.AutoFilter Field:=7
    Range("A4:CZ92").Sort Key1:=Range("A4"), Order1:=xlDescending, Header:= _
        xlGuess, OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
        DataOption1:=xlSortNormal
    Selection.AutoFilter Field:=5, Criteria1:="="
    Range("A4:CZ92").Sort Key1:=Range("A4"), Order1:=xlDescending, Header:= _
        xlGuess, OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
        DataOption1:=xlSortNormal
    Range("U4").Select
    ActiveSheet.Protect
End Sub

Private Sub worksheet_change(ByVal Target As Range)
Dim mytime As String
If ActiveCell.Column = 5 And ActiveCell.Row > 3 Then
    Application.EnableEvents = False
    mytime = Now()
    Range("F" & ActiveCell.Row).Value = Now()
    Range("F" & ActiveCell.Row).Select
    Application.EnableEvents = True
End If
End Sub

Ratcheting-List--Post-Copy-.xls