How can I prevent users from opening a spreadsheet that is already open by another user?

why don't you just take it off of shared use?

The spreadsheet is not on shared use. The spreadsheet is normally open all day long and users make updates to it. Sometimes, a manager opens the spreadsheet to make changes to it or other things. While the manager has it open, another user opens it as read only. The other users that have made updates all day long do not realize that it has been opened -read only-. This is the problem that I would like to eliminate. I want to write some code that checks to see if the spreadsheet is already open and if it is I want to kick the user out of excel immediately. Can anyone help with how can I tell if the spreadsheet is already open and not allow read only access but kick the user out instead?

Thanks,

David

You can do:

Save As > Tools > General Options > and then input passwords.

Would that do what you want?