This may be a simple question, but I can't figure out the code for it. When a user opens the workbook I am building I want it to see if other excel files are open and prompt a warning that no other excel files can be open while accessing my workbook. If they click continue then all the files will be closed and the active one will be the only file open. If they choose to not continue then only my tool closes. Also, if possible I would like the warnings to pop up with the application not visible and then regardless of the choice the application is visible again.

As I said this may be something simple. Thanks for any help provided.