Chances are some neighbor has an RF remote and it is picked up by your receiver. If that is the case, one of you needs to change the "address" of the remote & receiver. Hopefully you don't both have the same non-addressable units. I don't think ferrites will help you, since the unwanted signal is most likely picked up by your antenna. As a last resort, you need to reduce the gain of your antenna somehow (try some various tin foil shapes on/around the antenna. You can also try a different orientation or moving it around to different locations.
If your equipment is actually recognizing valid commands (changing channels, turning on/off by itself), it is highly unlikely to be random noise. One (or more) of your neighbors must have a similar TV and Comcast box AND they're using the same RF remote as you. OR, they have line-of-site into your TV room and their infrared remote signals are being picked up by your equipment. You can easily eliminate that possibility by blocking off your TV and comcast box IR sensors with tape or something, provided your own IR emitters still have good visibility to the sensors.
