just a thought but if it's an RBR problem. How come it doesn't affect the Toro Rosso cars?
Admittedly the TR is built at a different location, using different parts etc. But it was designed (initially) by the same man.
I'm finding it hard to believe it's an RBR problem. It seems to me it's more of a Seb Vettel problem.
3/4 cars show no problem in 2 races.
The one common factor I see is Seb Vettels' car.
Mark Webber hasn't had a failure during the races, maybe he has during practice (but many teams do)
Toro Rosso, they seem ok.