I have the same problem - with the same dishwaher but have been told by Smeg that I will need an engineer. I have been able to reset it a number of times but it trips again once it starts to wash. The reason they trip is because there is a leak somewhere although there is no water leaking from mine that can be seen.
Apparently there is a small tank underneath with a float which holds water and when the float gets so high it trips the Anti-Flood system.
Hitch
October 2008