Serious X5 Problem

[nsfdfiremed]

Hi, I am inquiring how many other X5 owners have experienced what just happened to me and if you know what the problem could be. I live in Wisconsin and for the last two weeks the temps have been well below zero (as in 20-25 below zero!) On Friday I was driving at normal highway speeds and everything seemed fine. I went to accelerate and had no power, a quick check of my gauges revealed that everything appeared at normal levels, temperature etc... But when I looked out my rear view mirror all I saw was a huge white cloud. I limped it over to the shoulder and called for a tow truck. It's now at a BMW shop awaiting repair. My first thought was a head gasket is blown. My temp though was in the normal range and when I looked at my tail pipes both had oil spattered on them. The weird thing is the tow truck driver had another X5 the day before with the exact same problem and 2 more last week, same thing. What is happening with the engines on these? Could it be weather related or a production problem? My car is a 2001 3 liter and has only 56k miles on it. Has anyone also experienced this and could provide any insight into it? Anything helps as I am concerned with what this could be and more importantly what it will cost to repair. Thanks for your expertise and advice.