Mini-Box Issue

I have a new Mini-Box that, a few weeks after installation and set-up, has started to quickly scroll through the channels when the up or down channel is pushed. The same for the volume - the volume goes up to full or to mute whenever the volume increase or decrease button is pushed. The previously installed Mini-Box was also doing the same thing. I have also switched out the Mini-Box, the cables, the TV and the same thing occurred. Only after I changed the Mini-Box power source to another wall outlet did the problem seem to go away. The Mini-Box is the furthest from the where the cable comes in the house and there is a split to the phone modem as the cable comes out of the wall to this Mini-Box. It seems to be working now, but is there any way to fix this so that I don't have to have an extension cord running to the Mini-Box?