KVM Switch interferes with usb drives

Does the KVM switch have its own power source, or does it draw power from the Mac? Have you tried swapping which KVM port plugs into the PC vs the Mac. Maybe one of them is used to draw power and the other does not. Maybe if you swap the KVM ports, the PC will provide the power.

You can use Applications -> Utilities -> System Profiler -> USB to see the power being drawn by each USB device.

Do you have a Powered USB hub you could put between your Mac and the KVM switch?

If the KVM has its own power supply, you can still try a USB Hub to see if putting the Hub between the KVM and the Mac will eliminate any USB bus interference.

You could try Synergy.

Synergy is software that lets you easily share a single mouse and keyboard between multiple computers with different operating systems (Mac, Windows, Linux), without special hardware. All you need is a LAN connection. It's intended for users with multiple computers, where each system uses its own display.

<http://synergy-foss.org/> $19 ($29 with encrypted connection and support)

<https://github.com/symless/synergy> free to build your own sources.

For awhile, many years ago, I used a TRENDnet KVM switch between my iMac and a Linux box. It worked OK for awhile, but it either failed because of a hardware issue, or a software upgrade (don't know which).

By that time, mostly did not need to use the Linux console (mostly ssh sessions, which were easily done from my iMac), and the few times I needed the console, I could just use the other keyboard, or VNC from my iMac to the Linux box to see the console via my iMac.

While I have not use Synergy, I did use Telnet (a Mac ONLY similar software product). Telnet allowed me to move my cursor off the edge of the screen and control would move to the other system (in my case between my iMac and my Macbook). It even allowed me to transfer the paste buffer so I could copy and paste between the 2 Macs. It was rather useful, as I did not need to tell the KVM switch to move the keyboard/mouse/trackpad between systems, just move my cursor to the other window like it was one giant virtual display.

Today, I just Screen Share my Macbook Pro to my iMac and access the Macbook Pro directly from my iMac.

While I no longer have a Linux box under my desk, I do have remote Linux virtual machine systems, and for that I use a VNC session to control the console.

And for my Windows test systems, I use Microsoft's Remote Desktop Connection (RDC) software to put their console sessions on my iMac.

So I've eliminated my need for a KVM and Synergy type software.

It's possible that you need an AC powered KVM.

By any chance is their USB2 vs USB3 ports and/or devices in the mix? I know I am out in left field and making wild guesses. I'm just trying to think of anything that could maybe upset the Mac's USB ports, or the external devices you are trying to also use.

I'm glad you got it sorted out. I have an IOgear KVM and it has been rock solid, but it is AC powered. I've been leery of the little non-AC powered models. I think your question provided some very useful information, for me, at least.