Hey there,
You may be able to use something like this in your ThisWorkbook module ...
<font face=Tahoma New><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> Workbook_Open()
<SPAN style="color:#00007F">Dim</SPAN> i <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">For</SPAN> i = 1 <SPAN style="color:#00007F">To</SPAN> Workbooks.Count
<SPAN style="color:#00007F">If</SPAN> Workbooks(i).Name <> ThisWorkbook.Name <SPAN style="color:#00007F">Then</SPAN>
Workbooks(i).Activate
ActiveWindow.WindowState = xlMinimized
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN>
<SPAN style="color:#00007F">Next</SPAN> i
Me.Activate
ActiveWindow.WindowState = xlMaximized
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>