Sooky

Hello all. If I have posted this wrong I apologise......... I am in Western Australia and have only just found this forum. I am totally at sea with my mp3 NWHD5. Previously I have had no problems to speak of with this machine. June last year my old computer with xp windows crashed and so I bought a new one with vista. I transferred all music files to my new computer but now I have removed all files from my mp3 and tried to load more new files on. They load no problems but I then get the words CANNOT PLAY TRACK ON THIS DEVICE. Please why is this happening. At first I thought it was because it was 64kbps.......then I thought it was only the atrac files. Most of my files are mp3. I have tried everything. Sorry not a dumb female but one just a little bit older than probably most of you and not up with all this latest technology. Is it because my files have transferred from another computer. There was no way to be able to use the authorisation option on my sonicstage version 4.3. Please what am I doing wrong. We can no longer listen to our music while riding our bikes. Any help would be most appreciated. sooky