I recieved the same error when attempting to install Nero 6, only rebooting *did* solve it for me. Later when I upgraded my Nero 6 to version 188.8.131.52 I received the same error again... this time I just close nero drive speed and re-started the install and it worked fine. I don't think Nero Drive Speed is included in the un-install process, since it would be running in the background if you use it, so it would still be running in the background when you install Nero 6, even if you reboot, since it has the tendancy of launching at startup. I bet you that this was the guy's problem.
Punch Cards -> Paper Tape -> Tape Drive -> 8" Floppy Diskette -> 5 1/4" Floppy Diskette -> 3 1/2" "Flippy" Diskette -> CD-R -> DVD±R -> BD-R
The Progression of Computer Media