I have an application in Excel that once run, takes over the excel environment, locks out all menus, disables shortcut keys, and leaves very little of the visible excel environment. User has access to all commands he needs for my program and that's it.

Problem occurs if user was say doing his taxes in another open excel workbook, opens my program and realizes too late that he is unable to switch back to his former workbook, or if using 2000 or XP, can switch back but no longer has his menus. Hasn't happened yet, but I can imagine the phone call when this happens.

Looking for code that would identify if a user has a file already open. And also that would ensure it does not detect the default workbook that opens with excel as an open file.

This would allow me to prompt the user to save his/her files and close them. Or to abort the opening of the program. This would be done via message boxes or forms, giving the user the chance to save+exit existing files, exit without save of existing files, or to abort program launch.