This message appears when multiple users are logged-in together on the same PC. This can happen when the Windows “Switch user” operation was used and it kept both the old user and new user logged-in. This behavior is due to the fact that SoliCall Pro is a special application that is connected to the virtual audio device driver and therefore only one instance of SoliCall Pro can be simultaneously executed on a single computer. To avoid this message simply use the Windows operation “Log Off” before a new user log in.