Microsoft Excel 97 includes built-in macro virus protection. This protection is enabled by default during installation. With macro virus protection active, whenever the user opens a workbook containing macros, Microsoft Excel displays a warning dialog box. This dialog box gives the user the option to not open the file, open the file but disable its macros, or open the file with macros enabled. If the user chooses to open the file with macros disabled, all macros in that file are completely disabled, not simply the Auto_Open routine.
All workbooks, including add-ins, opened by the user are subject to the macro virus protection feature. There is no way to programmatically disable it. Workbooks and add-ins opened programmatically and add-ins loaded using the Add-In Manager are not affected. This means that you could create a small add-in that simply adds a menu or tool to one of the built-in bars and have that command open your project. This prevents the user from being presented with the macro virus protection warning dialog box each time your add-in is opened.