Russian investigators, having pinpointed the cause of a December 2012 launch failure, have cleared the Proton rocket to resume commercial launches in March.
It is interesting that this failure of the Proton’s Briz-M upper stage was not related to two previous failures of that same upper stage. It is also interesting that the article does not describe what actions have been taken to correct the problem.
If I was a future Proton launch customer I would be very concerned. Three launch failures all related to the Briz-M upper stage, and all from different causes. This appears to suggest some fundamental problems with the stage itself, or with the company that manufactures it.