The Camel Honda rider lost the front through the Haysheds section at well over 100mph and slid quickly across the grass on his back before striking an inexplicably high edge to a gravel trap.
The force of the impact launched Barros several metres into the air before he rolled, rag doll like, to a halt - his RCV having self destructed alongside him. Barros was conscious but had taken a huge impact to his ribs and was clearly in pain.
Meanwhile, the Brazilian's temporary - and perhaps future - team-mate Chris Vermeulen
recovered from a poor start, from 14th on the grid, to take an excellent 11th on his RCV debut in his home race. The World Superbike championship runner-up had been as high as 10th, but was outfoxed by lone Suzuki rider John Hopkins
on the last lap after a long duel with the Anglo-American.
Five-seconds ahead of Hopkins were Fortuna Yamaha rider Toni Elias, Konica Minolta Honda's Makoto Tamada and Kawasaki's Shinya Nakano
- who all crossed the line less than 0.1secs apart - while Elias' team-mate Ruben Xaus, D'Antin Ducati's Roby Rolfo, plus WCM team-mates James Ellison
and Franco Battani completed the points scorers.
Kawasaki stand-in Olivier Jacque would finish 16th and last after outbraking himself at the Honda Hairpin, and then taking a pit stop, before returning to finish the race.
Full results to follow...