I had trouble when I first bought mine, several years ago, because my Adobe Reader wasn't up to date. When at length I managed to download a suitable version, the Child Ballads disk worked. However, when I got a new computer, I had to telephone to get something or other reset.

My impression is that this sort of nonsense is a result of copy protection. A similar thing happened last year with the Oxford English Dictionary CD-ROM. It stopped working, all over the world, because an upgrade of Windows was incompatible with Oxford's copy protection software. Eventually a patch was provided.