Engine head failure

[ScubaSteve]

So I figured id finally ask about this being its been about 3 month since my 01' x5 4.4 has ran. On a vaction the wife and i took back in august, from Sacramento to LA to Vegas, our car started to act funny. Being that I am an old chevy guy, i popped the hood and found that in my #4 cyclinder spark plug was hitting the head cover. While taking the cover off, i found that the spark plug threads stripped out and had also destroyed the coil pack. So we were only able to drive from LA back to Sacramento on 7 cylinders. This is not the first BMW that I owned that this has happend to. I had an 00' 323CI that did the same problem in the#2 hole. Ive searched for any others that have had the same problems as I and found that no one has had this problem(or atleast reported it). I love my BMW cars but am mystfied that this has happened twice to me. I have an R6 that Ive been riding, but now that its started to rain, I must now get this fixed. My question now is, when i get this fixed, are there any precautionary steps to insure that this doesnt happen to any of the other head spark plug threads or is it a matter of time before they just go out? I want to get a 650i but am concerned this will happen to another of my cars.