First, are you sure your source CD is not actually a CD Extra CD? I don't have Nero 5.5 installed right now, but I am able to copy a pure audio CD using AMQR on Nero 6. And since Nero 6 (neglecting the additional non-core programs like ShowTime) is just Nero 5.5 with more bugs in it, if it works on 6 it ought to work on 5.5 as well.
Second, whether or not your source disc truly is a CD Extra disc, to work around the problem extract all the audio tracks to your hard drive as .wav files (CDex
is free and easy to use software that will do this, although you can also use Recorder->Save Track... in Nero) and then burn the tracks as an audio compilation rather than a direct copy.
I see you have replied that the disc is a CD Extra CD since I composed this, and Matt has given you one way to work around it. Consider my reply as just another couple of options.