The ESP Guitar Company

Heya, I've recent brought a ESP Viper 1000 with the standard EMG pickups.. sounds fine on clean, but when distorted -- there's a constant buzz. Its a low buzz sound and particularly when recording, its quite loud. If you mute the guitar strings, its there. When you turn the volume off on the guitar it disappears, this seems like a pickup problem... anyone got any suggestions to sort this? Would be most appreciated :) Thanks