Can't use any other workbook anymore

[M.V.]

I made a application in Excel. It is an agenda and it gives a popup when necessary. The macro starts in Workbook_Open(). Then starts a loop (with Do Events) to check is time for a popup. It all seems to work well. But I can't use another Excel workbook anymore.
Does anybody have a solution for this problem ?

 

[Weaver]

Your first command should be to ensure the active workbook is the one you want the code to run in. If it isn't, don't execute the code.

Not sure if this'll work, since I don't know what you're doing, but it might be worth a try.

 

[M.V.]

The problem is when the application is running I can't open another sheet by just clicking on it. When I first open an empty sheet in Excel and then another application it works fine. But when I first open another sheet and then my just made application there is a problem. When I write something in a cell in the other sheet it appears in the new made application.