Try this: right click on tab, "view code" and copy/ paste
'-----------------------------------------------------------------
Private Sub Worksheet_Change(ByVal Target As Range)
'-----------------------------------------------------------------
Const WS_RANGE As String = "A1:A1" '<<< change to your cell
On Error GoTo ws_exit:
Application.EnableEvents = False
If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
If Target.Value = "ABC" Then '<<<< change value and file
Workbooks.Open Filename:="C:\Documents and
Settings\John\Desktop\test.xls"
End If
End If
ws_exit:
Application.EnableEvents = True
End Sub