"The problem with strangelet doomsday scenario, besides being very bizarre, is that no one has ever seen a strangelet. It remains a hypothetical particle. Previous particle accelerators that operated at lower energy than the LHC were actually better candidates to producing strangelets, and so far, we're still here."
"It is actually a very interesting idea in quantum field theory. It states that life, the universe and everything aren't the most stable configuration possible. Perturbations caused by the LHC could tip it into the more stable state (called the vacuum bubble) and all of us "pop" out of existence."

SOMEHOW, these answers don't give much comfort.