This happens whenever you recieve search results from users of the latest versions of Gnotella or BearShare. These clients send out extra data (bitrate and ong length) that XoloX can't interpet correctly, and all but the first returned MP3 will be 'corrupted' in the manner you describe. This effectively makes all MP3's from BearShare and Gnotella worthless, as you can't download them.

For more on this and other things, see this thread.