Unreadable (and unrippable) CDs

Like many others, I followed the Sony rootkit saga with interest, feeling relieved that as a Mac user I was probably immune to such stuff. But I guess DRM is inescapable. Recently I’ve purchased two CDs that play just fine in a CD player but are unreadable on my Mac (or on a PC). The first was Enya’s latest, Amarantine. I inserted it into my PowerBook, the drive made seeking noises for a few seconds, and then the CD was ejected. Hmm. Last weekend I picked up At Blackwater Pond : Mary Oliver Reads Mary Oliver. Same thing. Frustrating.
UPDATE: The folks at Beacon Press (publishers of the Mary Oliver CD) got back to me and said they hadn’t seen this before. So I decided to shut down my Powerbook and reboot it. Normally I just put it to sleep when I’m travelling; I often go for several months without rebooting. After this I was able to read the Mary Oliver CD, although ripping was unusually slow – around 1.2x. Sadly, the Enya CD remains unreadable.