problems with sony NW A1200

:?: Hi,
I've got a new Sony NW A1200, and loaded up my songs onto it for the 1st time and all was ok. The next time that i plugged it into the computer to update it with new songs and playlists, it seemed to update ok on the screen, listing new playlists, stating how much memory had been used, etc, but when I unplugged it, it was saying "no database found, please connect compliant software. I tried plugging it back in to the computer but it was again showing up on the screen as if all was ok. Has anyone else had this problem? Any suggestions?
Thanks

I am having problems loading my cd's onto the player. they are all saved on my computer & in wma format. I cannot change the format as they are copyright protected. When I try & transfer the files I get this error message:
An error occurred while transfering.
Transfers are not allowed.

Any ideas how to get round this?