Cognos and Excel

My company uses Cognos reporting software to generate reports from our data warehouse and exports them into Excel 2003. However, we have several users with Excel 97 and if these users have Excel 97 open when the Cognos report is running, the Cognos report will error out. I think there is an issue with having both versions of Excel open at the same time. What I need is a way to have the user have Excel 97 open while running the Cognos report, that exports into Excel 2003, without errors.
Thanks