This is not an error condition. It is an informational message. I agree that it is not a very clear or accurate message. It is telling you that the currently detected samplerate does not match the samplerate that was set in the project when it was last saved. Cubase does not directly control the audio sample clock rate of the audio device. The audio clock rate is set on the audio device either using physical switches or buttons or via a software control panel. The computer operating system driver for the audio device (typically an ASIO driver) reads and detects the currently set clock rate on the audio device. If the detected clock rate does not match the rate that was in use when the project was last saved, this message is displayed. I use a Roland EDIROL FA66. This has a physical switch to change the sample clock rate. The FA66 must be switched off, the rate changed, and switched on again, in order to change the clock rate. In MAC OSX there is a software utility to detect and configure Audio and Midi devices. This will also show the current clock rate set on the device. If I change the sample clock from 44.1 to 48 after saving and closing a project, when I open the project with the rate set to 48, this message is displayed. Because Cubase does not directly control the changing of the clock rate, there is no easy way to know what samplerate was set in a project when the new rate is different and this message is displayed. I always include a reference to the samplerate in the project title when I save it (for example NightJack48k.cpr) I also put a reference to it in the Project Notepad. So take note; This message will always be displayed if the current samplerate set on the audio device is different to the rate that was in use when the project was saved. Once the samplerate has been set correctly and the project has been saved, as long as the audio device rate is not changed, the message will not be displayed when you next open the project.