Computer Goes Haywire

SOON after I bought my 2003 BA Falcon Ute the heater would not work. That was fixed, but I began to have problems with the computer. All the dials would go out and the warning lights come on. I found that with a touch of the automatic window button the lights would all go back to normal, but the dealer could not find the problem and it still occurs. Now a starting problem has come to light on very cold mornings. It will start, but then die, start again, then die again, and finally there is no response when the key is turned. The computer has been checked by an auto-electrician and found to be fine. Any clues?