I had a problem that I solved and thought I would share this info. I had Nero Express and Intel's Application Accelerator (IAA) installed. Many times I was unable to choose the burn speed for Nero. It would lock in at 4x (the drop-down box grayed out), even though my drive is capable of burning at 48x and my media is capable of as much. It didn't always occur, but most of the time. To "unlock" the drop-down box so that I could choose the burn speed I would close Nero, eject and reinsert the media, then restart Nero again. Presto! My burn speed options are back, but then again, why the hell was it doing this in the first place?
It turns out that uninstalling IAA cured this problem. I'm not educated enough on this matter to provide a technical explanation. It just seems apparent that there is a conflict in having the 2 applications installed together (IAA replaces the native IDE drivers, correct?). I'm not sure if I would call this a Nero bug or an Intel bug. Maybe it's neither or both, depending on how you look at it. Either way, it's a good example of how mysterious "bugs" appear. I'm not going to complain because I've got it working again. In this case, I can live without IAA.