Have you checked that each of the songs plays ok on your computer? One of them might be faulty/corrupt which is mucking up the conversion process.

Are they all mp3, or are they another type or a combination of types such as wma, m4a/mp4, real, etc.?

Whilst most burners should be able to handle it, one of the songs might be 48 KHz instead of 44.1 KHz, or mono/joint stereo instead of stereo. If that were the case & your burner was struggling with it, then convert it to WAV & then to 44.1 KHz & stereo & re-add it back to the burn list.

In fact, converting all to WAV will not do them any damage & make it easier for your burner to burn them, instead of converting from mp3 in the process of burning, depending on whether your burner converts during burning or before the burn begins. Just my thoughts.