I have a Sculpt keyboard as well, and the way to fix this is just to move the wireless USB stick that's in your computer closer to your keyboard. I have mine at about a 40cm distance. If I place it over 100cm away I start getting sporadic connectivity issues, which result in delayed or dropped input. It also gets worse if you have a lot of things in the way between your USB stick and keyboard/mouse (duh). For example, if you place the stick at the back of your PC, and below your desk, the signal has a harder time going through the chassis and desk to reach your keyboard/mouse.