If you are having a problem with pops and clicks during playback, than this is most-likely a problem with your audio buffer size being set too low. This usually only occurs when you are using an external library with Notion. You will want to increase your audio buffer size. Please be aware that increasing your audio buffer size can create more latency. This really only becomes an issue when you are doing MIDI entry with an external controller or using the NTempo function. You want to increase the audio buffer size to the point where the audio clears up. You want to keep the audio buffer size as low as possible but high enough to clear up the problem. Here are some instructions for doing this:
Go to Notion>Preferences, Audio and drag the "Audio Buffer Size" slider to the right. For Notion 5, the option is called "Buffer size."
Open the control panel for the driver or your audio interface. If you don't have an option for audio buffer size, you will want to look for latency. If you are using an on-board soundcard or an audio interface that does not offer an ASIO driver, you can download and install a free driver called ASIO4all. www.asio4all.com Once installed, set this to be the ASIO driver inside of Notion and make sure that ASIO4ALL is directed to your interface by clicking the small icon at the bottom right-hand corner of your screen in the startup tray to open the ASIO4ALL control panel. This is also where you can increase the audio buffer size in ASIO4ALL.