The very first thing you should do is clean the ground connections under the Central Electronic Unit (the CEU is the contraption which holds all of the relays and fuses), and at the driver's and front passenger's footwells. Not only clean the gronds, but you should take the small piece of metal which the ground connections attach to and clean it and it's connections to the chassis.

As Steve noted, you could also have ignition switch trouble. The ignition switch has multiple contacts whcih don't all fail at the same time.