I have the 2.4GHz version and noticed that after a while of using it the window I'm working in will get all messed up. Basically horizontal lines get chopped and repeated when I scroll up or down. If I switch to a new app or window it returns to normal. Also, taking a screen capture using Grab takes a minute to process. I can move the cursor, no beachball, but nothing happens. Even the clock stops. This just started happening. Any ideas? Restarting seems to help get it back to normal, but it returns after a few days of using/sleep.