I just encountered this same problem with my floppy drive this weekend in an Antec SLK3000-B case. The floppy drive worked out of the case, but not in the case. The problem was this: The front part of the case where the floppy drive slid through had a metal support tab/shelf. This support shelf was pinching the floppy drive too tight and kept the exposed "wheel" from turning. I slightly bent the support shelf downward so that it didn't exert pressure, and now everything works great. I suppose your DVD burner could have the same problem if some of the mechanics are exposed.