The bundle uses the same drivers as just the mouse and the keyboard separately but it shares the receiver between the two.
It just could be an issue with the Duo's receiver, I dunno.
Phenom II 940 Black Edition quad core @ 3.5Ghz
4x2 Gigs Patriot PC2 6400
Cooler Master HAF XB EVO,
Some other stuff,
Even more stuff,
If the automobile had followed the same development cycle as the computer, a Rolls-Royce would today cost $100, get a million miles per gallon, and explode once a year, killing everyone inside. --Robert X. Cringely, InfoWorld magazine