When you install SharePoint, it typically creates an entirely new IIS Site and assigns that one to the standard ports (80 and 443). The Site that your other applications are assigned to is probably not even running anymore. You could reassign the ports on that site and start it up, and give your users new urls. But SharePoint is such a resource hog that I would not recommend running any other application on a machine with it installed - you should move your Laserfiche applications to another server.