Maybe you can use the code at this site.

http://support.microsoft.com?kbid=138621


"budi1568" wrote:

of ObjectHallo
Is there anybody can help me since I am new in VB and having case as follow:
I am working with two workbook where when I open the 1st workbook it will
open the second one. The problem is if the second file already open I got an
error message : Run Time Error 1004.
Methode 'OPen of Object 'Workbooks' failed

Private Sub Workbook_Open()
Workbooks.Open Filename:="O:\2009 Budget\Forecast 2008\Forecast Q Rep
08.xls" _
, UpdateLinks:=0
End Sub

Thanks for helping me