Radio keeps cutting out for 2 seconds

This or some reason the radio (or CD or tape whatever) keeps cutting out for about 2 seconds. The display stays on the screen - its just the sound that cuts out. Touching the brake pedal seems to cause it to happen too. Is it electrical / could it be the solenoid / bad earth .... or what.

Glad of any help.

Its a 1999 Discovery TD5 by the way.

dodgy multiplug connection on the back?