Hi David,

The discs that give problems are those which have a video track, usually showing a live performance or a mini-documentary on the making of the disc.

Two examples are: The Rolling Stones 'Totally Stripped', and The Beatles 'Rubber Soul', which has a track 'Rubber Soul Mini-Documentary'.

I think the addition of video tracks is becoming more common with reissues and remasters.

Cheers
Barry