The speccy was my starting place too. When I got my speccy in 1984, it would have been hard to imagine I would one day be able to play Jetpac, Atic Atac etc anywhere I go. Thanks Metalbrain, great emulator!
I've had the A-DATA 4GB card for about one month and I've not had any problem with it at all - it works fine. Maybe you had a faulty A-DATA card or a card reader that just didn't like it.