how's the problem with ur car? if it's not solved yet, try looking at the flywheel sensor. i had a similar problem a while back, and yes, the diagnostic machien couldn't find it. my mechanic actually had to check all the sensors, one by one. and after 2 days, he found out that the flywheel sensor was faulty.
btw, did u check for the 'over-ride switch' under the front passenger seat? press it and try to start the car. at times, because of some electrical faults, the system will switch it off. by pressing that switch, it might work (some times).
my 2 cents worth.
thanks & happy days