Okay, about that keyboard …
The setup I have is … not straightforward. I have two computers, a tower running Linux and a Mac mini. I have a single keyboard and mouse plugged into a KVM switch (an industrial 8-port unit I aquired mumblely-mumble years ago), but each computer has its own monitor. I also run Synergy on both computers to allow sharing of the keyboard and mouse across both computers. It will also allow you to move the mouse from one computer to the other (and supports “cut-n-paste” operations between the two computers). It's a neat program and really, the KVM is there when I need to shutdown in the event of a power outtage (and when I boot the systems back up, before I get Synergy running).
The KVM expects PS/2 style connectors, but both computers need a USB converter. This all just works and I rarely have issues.
Until I do.
This time, it turned out to be the cheap USB converter on the Linux system that just … I don't know, gave up the ghost or something (thank God! I was fearful the USB ports might have been blown out). I can work around it with Synergy, but it's a bit of a pain initially (boot one computer, switch keyboard/mouse to other computer, boot that one, switch keyboard/mouse back to get Synergy running). So now that I'm back up and running, I just need to get a new USB converter and maybe this time it'll last longer than a year.