Excel VBA Query

We have a spread sheet in which after a cell has had data entered into it the cell is protected and a password is required to make any further changes.

This is achieved by the following Macro.

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim cell As Object
    For Each cell In Target.Cells
            ActiveSheet.Unprotect "qaupdate"
            cell.Locked = True
            ActiveSheet.Protect "qaupdate", DrawingObjects:=True, Contents:=True, Scenarios:=True _
        , AllowFormattingColumns:=True, AllowFormattingRows:=True
    Next cell
End Sub

This locking by cell is proving too restrictive on the normal data user and they have asked if there is a way to lock down by Row.  i.e. as soon as you go to another line the line that was in use locks for normal use, which allows the initial entry to be corrected by the original person if they spot an error in a cell prior to completing the entire line.

Hope this makes sense.  How could this be accomplished?