Sascha: "Already-running" means the application is already open when you try to capture its audio. Without the Instant On component, Nicecast (or Audio Hijack Pro or Airfoil) then need to relaunch that application in order to capture its audio. We always recommend installing Instant On, which removes the need for the source app to be relaunched, but it was not immediately available on Mavericks.

See the update, however, for versions of the software which contain Instant On.

Håvard Pedersen: It's not likely that the screensaver itself has anything to do with that - you'll want to test with other screensavers. If you can nail it down to PongSaver, get in touch via our Support system.