One of the most highly touted features of the Zune music player has been thrown into question.

Some Zune users have been reporting that the music sharing feature via Wi-Fi doesn't work with quite a number of purchased songs.

Informal testing by Jason Dunn at Zune Thoughts has shown that a number of songs from Sony and Universal can't be shared.

He downloaded 10 songs, eight from the top 30, and found that only seven songs could be shared, but only five of the eight from the top 30.

He also reports that one source complained only about 50% of songs could be shared.

There is no information from Microsoft or on the Zune Marketplace about which songs can be shared and which can't.

The message that flashes up on the screen when a song fails to send, according to Engadget, is “Can't send some songs because of rights restrictions”.