Multiple apps calling single instance class

Question

Hi, I've been looking for more then 3 days for a simple and elegant solution for the following problem: I'm building a huge CRM program with more than 200 forms in it. If the user launches the app, he has to log in so I know his user rights within the application. Now, this all works fine, but I want to split the exe up in multiple exe's. Let me give an example. When the user starts 'Addressbook.exe' the first time, the program (underlaying class) asks the user to log in. When the user starts the 'Invoicing.exe' and the Addressbook is still open, the invoicing program has top get all user rights from the class. When the addressbook was closed (so the login info is gone), the system has to ask for a login again. This has to work in all directions for more then 10 exe's. Anyone an idea how I can get this to work? Actually, each exe runs in its own thread. But they should look for this specific thread which holds the login info and user rights. Greetings, Sigurd