Unprotecting downloaded music

[TEAK36]

A colleauge of mine who is a bit of a technophbe has just purchased a Sony MP3 Player, but is having trouble getting music to play on it.

He started by purchasing some downloadable music from Tesco's and transferred them to the player using the Sonic Stage software which came with the device.When I plug the MP3 player into my PC I can view the music files (all WMA), but none of them appear on the screen of the player. I tried using Sonic Stage to transfer the music again, but it wont let me do it as it says the music is protected.

The player is working correctly and I have successfully ripped music from a CD and it plays ok on the player.

Is there any way around this? Can I unprotect the music files?

Any help would be most appreciated.