I have a 2006 Audi A6 2.7 TDI Quattro and from time to time the electrics start blinking intermittently. The headlights, tail lights, instrument panel, MMI, all start flickering, but to date I have not felt that the car engine or power is affected. It happens on rare occasions and to resolve the situation I pull over, turn off the ignition and remove the key and then re-start. it seems to do the to trick, but its not a good feeling.

If it was the alternator at fault, surely the problem would be a more consistent? is there a fuse that governs the above? The condition seems to be sensitive to the instrument warning panel indicator, as I have noticed that if the windscreen top up fluid or brake pad warning signal (need replacing soon) appears, it provokes the condition above.
Any ideas?