Why doesn't Excel load MS Outlook object library so I can email within the workbook?

I have an excel workbook that sends one of the sheets as an email. Before it sends the email, it checks for the version of Excel, then loads the appropriate Microsoft Outlook Object Library (12.0 or 14.0). This has worked perfect on both Excel 2007 and 2010 for the last two years. Recently, a user upgraded to Excel 2010 Home and Business. Now, when the workbook loads, it presents an error that says it can't load the Outlook 14.0 Object Library. The object file (msoutl.obj) IS available and in the correct folder. Does anyone know what might be the problem with this user?