1999 Renault Laguna

Brakes problem
1999 Renault Laguna V8 Two Wheel Drive Automatic

hi hope you can help. I have just changed the discs and brake pads on the front of the car, when I start the engine everything is as it should be but as soon as I press the brake pedal the serve light comes on and stays on, if I restart the engine it goes off but then comes on again when brake is pressed. Sometimes it doesnt happen, any ideas on what this could be, have cheked brake fluid and double cheked installation of discs and pads. Any help more than welcome thanks!
April 29, 2010.

Have the vehicle plugged into a diagnostic computer to check for fault codes stored on the cars computer

Dave H
Apr 30, 2010.