Technical problem of the day....

Back in November, I picked up a Zonet KVM3332 KVM switch at Fry's. It has ports for two systems, USB ports for the keyboard and mouse, and audio inputs. I mostly use it to switch the video input to my monitor.

Since I've bought and installed it, I've been hearing a constant hum and some occasional whistling. It's audio noise that the KVM is generating. And it's getting annoying. I looked online and can't find any explanation for it. Zonet's web site says the unit is discontinued, and nothing about the noise.

(When I bought it, it was an opened box. Maybe this is why the previous owner returned it. Ah well -- you get what you pay for.)

And now that I discovered the hot key to switch input sources -- tap the left Ctrl key twice -- it can be darn convenient when I have the laptop docked and am doing work on both systems.

Is there any way to get rid of these noises? (Besides swapping out the KVM, of course.)