"Reject: Not Audio CD" But it IS a playable, new CD

[TDWilliamson]

I have a Nimbie 21, and have successfully ripped over 100 cds, but now it has rejected 3 or 4, with above error message, all of which are playable, new CDs. Could it be that because no Metadata is found, it rejects them? I have no idea why. thanks in advance.
TD

[Spoon]

Re: "Reject: Not Audio CD" But it IS a playable, new CD

Without running dBpoweramp, manually insert an audio cd, and look in Windows explorer at the drive, it should show as an audio cd, does it?