I can no longer import CDs into iTunes for Windows.

I get the following message (I've tried importing different CDs): "Error occurred while converting the file "xxx." The disk could not be read from or written to."

I'm using the latest version of iTunes and Windows. My iTunes library is on an external hard drive, and I have no problem copying other files to that drive. The permissions for my iTunes folder on that drive seem to be OK. I've never had problems importing CDs into iTunes before. What could the problem be?