I have discovered that even though a usb keyboard or mouse WILL work correctly when connected to the comp directly, they may not work or will delay or stop the boot process when running thru a KVM switch. It seems necessary to use only "generic/plain" keyboard and mouse to stop the boot hang problem. My Microsoft wireless mouse was the total cause of this problem when used thru an electronic KVM and then thru another KVM with all mechanical switches. A "lighted" keyboard and another with the "special" keys that take you to your home page..etc, also gave some trouble! Seems counter-intuitive, but try different mouse and/or keyboard into the KVM and see if that does it. :>)