Have you had this done? http://ducatiforum.co.uk/f6/mutley-recall-replace-keyless-ignition-unit-4595/ Sounds to me the bike "lost" the key signal and turned the bike off?
Once started, loosing contact with the key does not cause the bile to switch itself off. I would suggest that this would be a disastrous design philosophy for Ducati to adopt. Imagine fast lane of a motorway and a key malfunction and the ensuing court case that may result ?. Sure there are many examples of Multis going dead due to an ignition system issue (red switch), but not because they have lost contact with the key. The bike simply warns you by way of a message on the dash that it has no key and carries on regardless, I have left my key on the bench in the garage and got a good mile away before noticing and returning for the key.
Last month whilst waiting to board a P&O ferry my mates Pan would not start. After fiddling for some time the 'loader' came over and said that sometimes the radar onboard the ship interferes with immobilisers and recommended pushing the bike to the farthest part of the quayside and trying again. Sure enough that did the trick and he has never had the problem again. So here's a thought. Twin4me was riding past a speed camera at the time and perhaps there was some radio interference that operated the immobiliser.
That might have explained the first time, but not other's in different locations with nothing like that around. I think it's probably a similar issue to JRW's, it was normally on slow down, overrun.
