JBR,
The mechanical switch connects one way and disconnects the other way. So, if you have an OS that will notice that the KB is disconnected you will get that result. The electrical version has circuitry that fakes out the keyboard circuits in the computer and even supplies the response code required during bootup. I quit using mechanical switches about the time 98 came out for that exact reason.
gosemer,
You can get results like that when the power supplied is not enough. Some KVMs have external power bricks to supply enough. Don't know if the Belkin might need one, I've never used one of theirs. I have one Cybex that is picky, it goes bonkers if one particular machine is the only one powered.
Ed Fair
Give the wrong symptoms, get the wrong solutions.