Keyboard & Mouse from Belkin F1D104 KVM Switch not recognized

I've got the Belkin F1D104 SE 4-port KVM switch with a Compaq Presario SR2150NX winxp Vista & an IBM Thinkpad winxp & an Emachines T1842 winxp & a HP xw4300 Workstation winxp.x64 all connected with no problems but when I attempt to swap out either unit with another PC... Gateway GM5091e winxp - HP m7160n winxp - IBM E-26100 - Acer AM5100-U5201a ... neither one recognizes the keyboard or the mouse coming from the KVM Switch but all four recognize the keyboard & the mouse on stand-a-lone connect. I've swapped out the cables and even the KVM Switch and even changed ports on the KVM Switch to no avail. NOTE: The Gateway GM5091e was recognizing the keyboard & the mouse for over a year as recently as July 2013... then for reasons unknown it just refused to do so. I called Belkin and they have no answers. I know this is old & antiquated technology but does anybody have any work-a-rounds?

I've used a Belkin kvma switch for years. But it's only for 2 machines. Basically a glorified Y cable. But it was working since the 90s until I took my systems down in February. Anyway, how do the machines connect to the switch? All the mice and keyboards are PS/2 style correct?

"yes"