I have written a program to automate a few things in Excel with Visual C# 2008 Express Edition. My program is targeted to .Net 2.0 as this is what the company computers all have installed and upgrading is not an option. On the development computer I have Office 2003 basic installed but the company computers all have 2003 pro. In searching if there were different PIA's for pro versus basic i didn't find anything. I did notice that security settings dictate that the user have admin or power user priveledges but all users at my company have power user priveledges. Everything works great on the development computer but once I try and run it on a company computer it won't work, it just instantly crashes. So I remarked out all the Excel specific code except the using statement and I left the reference to the Microsoft Office 11 object library and the program didn't crash anymore. As soon as I un-remark any Excel specific code (Microsoft.Office.Interop.Excel.Application xApp = new Microsoft.Office.Interop.Excel.ApplicationClass();), the program crashes on the company computers. Can anyone help me with this frustrating problem?