I'm with you on the group project thing. Somebody always ends up being a slacker, and someone always ends up carrying way too much of the project because they care about their grades.

As for this situation--there is no way my child would be getting a D on a grade because some kid smashed the project. Particularly since it happened IN school!! Hopefully you'll make some headway with the conference. If not, I'd be at the principal and moving on up the line until somebody with some common sense acknowledged that a child who is this destructive a) has behavioral issues and b) should not be in charge of other kids' grades.

Good luck. Please let us know how it happens.