Huh. I don't have an explanation for you right off the top of my head why it would act that way with files waiting to be written to the CD, unless the system was in a tight loop trying to make the CD drive come 'ready.'

The "smooth scrolling" takes a fair bit of CPU power to implement, which is why I asked about something else hogging the CPU. Since you checked for smooth scrolling being enabled, the only thing I could think of was something else using quite a bit of CPU cycles, which would deprive your IE from getting all the CPU cycles, which would make it "jump."