Private Sub Worksheet_Change(ByVal t As Range)

Application.EnableEvents = False
CheckCol t, "E"
CheckCol t, "G"
CheckCol t, "W"
CheckCol t, "AA"
Application.EnableEvents = True

End Sub

Private Sub CheckCol(tr As Range, col As String)
Dim b As Boolean, t As Range
Set t = Intersect(tr, Columns(col), Me.UsedRange)
If Not t Is Nothing Then
  For Each t In t
    If Not IsEmpty(t) Then
      If IsEmpty(t.Offset(, -1)) Then t.ClearContents: b = True
    End If
  Next
  If b Then MsgBox "Текст вставлю сам", vbCritical, "Ошибка ввода данных"
End If

End Sub