Sorry not to reply a little sooner, yesterday was "girlfriend has Sunday off".
Next, thanks for taking the time to answer each of my Q's. It's unfortunate that none of the things that I have had cause problems in the past seem to be what is plaguing you, except maybe the lowly USB to PS/2 adapter.
Why don't you try a PS/2 mouse? (Or have you already?)
-- I am using an all USB set-up because I couldn't get any PS/2 keyboard to work & my PS/2 mice/trackballs had sporadic problems.
Mine is an IOGear "MiniView™ Extreme Multimedia KVMP"
I bought it for the speaker switching, w/ the microphone & USB switching as added benfits. I have had it almost a year (I think) & really like it. My 2 minor complaints are: (1) I get so used to using the 4 buttons that I can't remember all the keyboard controls for controlling the 3 (KVM, S, & P) things separately. (2) It's so small & light that I have to put a small weight on top it to keep its cables from tilting it up & threatening to drag it off my desk.
I knew when I bought it that it is USB & accepted that as price of getting the other features it offered. As result, I had to switch from a PS/2 wireless optical mouse I really liked, back to the regular USB trackball it had replaced. I also had scrounge a Compaq USB keyboard whose backslash key placement I hate. If I were shopping, I would look for a rechargeable wireless optical trackball w/ at least 1 wheel placed in a friendly relation to the ball & of course a USB ver. of my orig. BTC keyboard.
One thing that is especially nice is power failure recovery: Our local Pwr. Co. seems to be offering a free service to "Winders" usees (we all "know" that their machines "should be rebooted once a week whether they need it or not") -- it periodically sends glitches that reboot everything in my house. So far, when the Pwr. Co. decides that all the computers in my neighbor need this service, my network comes back up fine. However, the various instructions indicate that by rights everything should be shut down & then turned back on sequentially from the wall out.
Perhaps you might try that:
Power down everything & then bring each back up in the order specified by the KVM instructions (& w/ any specified delays betw. boxen).
BTW, I did follow your link & am impressed w/ your choice -- it looks like a really nice piece of equip.
Also, thanks for asking a Q that got me thinking about what I do & don't like about my current set-up.
1. "Reboot" in KVM specified order.
2. Try a PS/2 mouse.