Thank you tadad1, I have since found your, How To - Removing Memory Hack' and have followed the instructions, my results are: 1 x 4GB player was actually 2GB player, the 2GB player was 1GB and the worse one was a 1 x 4GB player that was actually only a 1GB player!
It also cleared up the txt file problem - I can now read txt files OK!
I will look out for batteries in the hope that I can redeem something out of this awful situation. At least it isn't guesswork anymore and I know EXACTLY how much music I can put on them without them being corrupted!
Thank you for all your help. xx
