I have an Excel 2003 format spreadsheet with quite a bit of VBA code to
validate user entries, create reports, and as code behind several userforms.
I've got everything working fine, except it the user has a second spreadsheet
open in which case my login userform fails with an error 9, subscript out of
range error message on the following line.

Workbooks(1).Worksheet("Price Plan").Visible=True

Any idea on why my code is failing, and how it can be fixed?

TIA,

Ken