Erratic Logitech unifying receiver (not what I thought)

I had an annoying problem with my M510 mouse and receiver. The mouse was intermittent in response and frequently not recognised. At first I suspected drivers and software but after updating and reinstalling driver/software several times and trying on other computers I thought maybe the receiver had become faulty and got a replacement. That worked better and was always recognised but after a short while the mouse response would become intermittent:

I eventually found an article that suggested that electrical noise from the computer might be the cause and because of the small form factor of the receiver it's circuits were too close and interference stopped it working properly. I pulled the receiver as far out of the USB port as I could without losing connection and things improved. I added an extension cable and the mouse response was again perfect. It might have been obvious to some people but it didn't occur to me. Anyway I thought I'd post this in case it helps someone.

Oh, the original receivers behaviour didn't change when I tried it in the extension so it was on the way out anyway.

Here I had the same problem with my Asus WT465 Wireless mouse. Not (I guess) because of intermitting frequencies from the PC, but more because the mouse was more or less hidden by the casing of the PC (which is situated under my desk).

For years I used an extension cable as well and put the receiver on my desk. In my newer monitor there is a sinple USB hub in the stand of it and so I used that for mouse-receiver and (wired) keyboard. Which functions very well!