S60, MY07, dashboard and engine stopped working

[ggo]

This morning, while driving on the motorway with ~120 km/h, the dashboard of my S60 just stopped working: all the instruments looked as if I had pulled out the key, but radio and RTI-NAv kept on running....
Then I realized that the engine stopped running, too. After stopping on the emergency lane and restarting the engine everything was fine again. I stopped at the Volvo-dealer and they checked if they could find any stored error code, but everything seems to be all right. The dealer seems to have no real clue...
Any ideas?

Thanks in advance,

Guido