Issues running 2007 macro in 2003

I have a macro created in excel 2007. when I or anyone else tries to run this in 2003, you are thrown off of the spreadsheet. I am thinking there is something in the macro that was not available or something. I tried to save it as a 97-2003 spreadsheet, and that didn't work. then I tried to save it as a macro-enabled spreadsheet and now you can't even open it in 2003 anymore! This is the macro:

Option Compare Text
Private Sub Worksheet_Change(ByVal Target As Range)
    If Intersect(Target, Range("F:F")) Is Nothing Then Exit Sub
    Application.EnableEvents = False
    On Error GoTo exit_proc
    With Target
        If .Value Like "*outside op*" Then
            MsgBox ("WARNING: Verify all outside operations with office before parts leave shop!")
        End If
    End With
exit_proc:
    Application.EnableEvents = True
End Sub

can someone help?? I'm so confused! And I gotta get this fixed a.s.a.p or we are gonna have a lot of parts that are not logged!

Could there be an issue with that particular computer's 2003 version? I haven't tried running it from any other computers with 2003 other than the one that would actually be running the spreadsheet more often.