We do have filters but I haven't heard of ferrite toroids. I'm willing to try anything. Could you explain a little further?
I'm going to guess that you are talking about DSL filters -- The ones you plug into the telephone jack to separate the phone and data signals. The filters I'm referring to are ones designed to attenuate an interfering signal and they can be connected on the various interconnecting cables between your computer and all its peripherals. Unfortunately, solving prolems like this can often be very difficult and require custom-made filters, and trying to diagnose at a distance is even more difficult.
Ferrite toroids are little rings of ferro-magnetic material which can act as a sort of filter in themselves by just wrapping the end of a cable through the ring a couple of times. In fact if you've seen something like the end of the video cable on a monitor which has a small cylindrical "bulge" just before the plug, that cylinder is concealing just such a ferrite toroid.
The first problem you face is that you don't know exactly
which part of the system is picking up interference and giving you trouble. You could try to narrow it down a little by disconnecting everything from the system that you don't actually need to test -- Printers, scanners, USB leads which aren't going anywhere, USB hubs which can be removed temporarily, speakers, etc. If you find it then works O.K., start reconnecting one at a time and test again at each step. Until you know exactly where the interference is getting in, you can't do much about stopping it.
