Wrote about these D9 problems a lot last year around this time, but I'd say its definitely related to voltage/heat and certain boards/chipsets may induce death sooner than others. I had 2 kits of Ballistix and 1 kit of Buffalo FireStix die on me....I've long since swapped them out for much cooler G.Skill. The older D9's were placed into a backup and I suspect they are starting to flake out again. Anyways, clearly flaky ICs but at the end of the day I was extremely pleased with Crucial's RMA process, so I wouldn't hesitate to buy from them again.
