I have just bought a Belkin Flip 2 port KVM. Functionally it is almost there except I have a keyboard sticking problem. So if I type the word 'Hello' it will often (about 25% of the time) output 'Hellooooooooooooooooooooo'. If I plug the keyboard directly into the USB on the computer I don't have this problem, only when plugged into the KVM. I feel like it is a USB speed problem.
Followup
It appears I have the same problem with the mouse, it will jump from one side of the screen to the other as I move it. The mouse is annoying but half as much as the keyboard.
Best Answer
First thing I would check is the power management on the USB's in Device Manager. Make sure this is turned off.
Also, have a look to see if there are any new drivers for the USB available from the manufacturer. I've seen this kind of problem before on XP and updating to the latest 2.0 drivers has resolved it.
Another thing to try would be to swap the cables from the KVM to make sure it's not a problem with the Belkin as well. As all is working in the desktop but not the laptop it could very well just be some duff cables.