Wave Corrector was unable to obtain a reliable noise profile.
The noise profile is used by the Hiss and Hum filters and an incorrect profile will cause poor performance of these filters. Therefore, if you intend to use either of these filters, you should first ensure that the noise profile is valid by using the 'View Profile' command.
If the noise profile includes any musical content as well as the noise, capture a new more representative profile.
See Waveform-Edit Noise Profile for more information.