There are many complaints on various forums about people having issues trying to access their CD drives from iTunes. I have had this problem myself and ended up getting around the issue by burning on another computer and copying files, which is a real pain. However, I recently realised that the problem was actually far simpler than first thought.
The problem I was having was that iTunes could recognise that a CD drive existed, but couldnt access it. I was distracted by the fact that I had recently upgraded the operating system on my computer from Win XP to Vista, and then with a new computer when I experienced the same issues, that I had upgraded from Vista 32bit to Vista 64bit. What I didnt pick up on though was that every time I had tried to burn a CD in iTunes, I had VMWare or VMPlayer running - and that the active image was accessing the CD drive.
By disabling the CD drive on these images, iTunes began functioning as expected, and I could burn CDs again. Simple really - not sure why it took me so long to work that one out, but hopefully it will help you.
