I have heard apple didnt have ECC protection for the RAMs on their Mac machines until quite lately. this is the kind of failure or hard disk failures that are more likely to kill a ship at critical moments.

people think highly of Unix machines but thats because they dont
themselves have to install the patches that come along. a friend
who owns one of every type of machine says Sun issues a patch a day on the average just like MSFT. and my Ultra10 needs a periodic reboot too.