I think some bad pixels can result from getting struck by cosmic rays. So a camera/sensor/whatever can be tested fine and then shipped and this can happen during shipping. Since there cosmic rays are partially shielded by the atmosphere, there are more cosmic ray events at higher elevations. This means that during air shipping, a camera is exposed to more rays than it is while sitting at Leica HQ. So it is feasible that a camera that is tested ok develops a fault after testing but before purchase.
I'm pretty sure CMOS sensors are also vulnerable to this kind of thing. Where I think CMOS differs (as was pointed out earlier) is that if they develop a dead pixel, the whole column doesn't go out. I don't think the whole column is actually dead, it's just an artifact of how CCD's are read out. I'm pretty sure once the dead pixel is mapped out, the column will return.
I'm not saying Leica knows what they are doing. I'm just saying that this doesn't necessarily mean that they are clueless and suck at testing.
Oh, and it sucks that this happened to you (again).
I'm pretty sure CMOS sensors are also vulnerable to this kind of thing. Where I think CMOS differs (as was pointed out earlier) is that if they develop a dead pixel, the whole column doesn't go out. I don't think the whole column is actually dead, it's just an artifact of how CCD's are read out. I'm pretty sure once the dead pixel is mapped out, the column will return.
I'm not saying Leica knows what they are doing. I'm just saying that this doesn't necessarily mean that they are clueless and suck at testing.
Oh, and it sucks that this happened to you (again).