In summary: while we need to consider every possibility with extreme skepticism, when something like this happens, by definition it is an extremely rare event. Therefore, while the argument "that would be extremely rare" provides a necessary skeptical perspective, it doesn't invalidate the claim (and, for those playing on conspiracy-theory "logic", actually validates it).
However, it is important to remember that *something* happened.
If we take the view that EVERY possibility is virtually impossible, then the only factor left would be pilot error!
From the accounts so far it appears as though the most likely reason for the problem was either engines, electronics or fuel.