Originally posted by GeneralZod
I have imported some CDs using iTunes while not connected to the internet.
There's your problem. You need to be connected when you import the songs, because that's when the file names are created. The CDDB is now seeing individual files, not the entire CD, which is what is needed to identify the disc.
I think your only option is to reimport the tracks, connecting to the Internet when you do so. Otherwise you'll have to manually change the file names, which means a lot of typing.