The "Waiting for: System Event Notification Service" message typically appears when Windows is shutting down or restarting. In your case, if the message is appearing when you are trying to log out, it is possible that the System Event Notification Service (SENS) is not responding properly.
Here are a few steps you can try to resolve the issue:
1. Restart the SENS service: Press Windows + R, type "services.msc" and press Enter. Scroll down to the System Event Notification Service and right-click on it. Click "Restart" to restart the service.
2. Disable and enable SENS service: In the same Services window, right-click on System Event Notification Service and click "Properties". Change the startup type to "Disabled" and click "Apply"...