Ok, so I have nothing running (not counting the few programs in the notification area) - no AIM, no Winamp, no torrents; just the program to burn.
I decided to be brave and try it at the default (8x) speed and it cleared without any errors - but that's happened before and when I go and look at the files, not all of them will play. Such was the case again here. If I try playing a file it apparently doesn't like, it just freezes up (this happened with my first attempts to burn Naruto files).
I quit with 8x - gonna try it at a lower speed this time and if it doesn't work, then I'll have no idea what to do...