The PlayStation 3 system could not read the disc as it is not supported.
Try cleaning the disc. Make sure the disc isn't scratched or smudged; if it is heavily scratched, the disc may need to be replaced.
If you continue to have issues, the files on the disc may not be supported by the PlayStation 3 system. Select the type of file you are trying to play to learn which ones are supported by the PlayStation 3 system.