I don't think this just relates to Dane-Elec cards as this happened to me some months ago and as it was a new Sandisk card (which have a lifetime garauntee), I took it back to the Staples who not only immediately replaced the faulty card but also copied my work from the locked one to another new card, (although I'm not sure how they did this).

Needless to say I was very pleased with their service.

Audrey