Ok, the PDF24 Creator uses a Windows Service to redirect print jobs. You can find the service in the Windows Service manager. The name is PDF24. This service must be in a running state in order to get the PDF printer to work. Did you stop the service or do you see some system errors in the Windows event viewer? If the PDF24 service is not running, then the PDF printer will not work. Normally the PDF24 pops up a message box that tells you, that the service is stopped and there is a button to restart it. This is implemented in the current version 8.4.1.