Apple upgrade fries bottom memory slot

A friend of mine has a Mac, and after upgrading to one of the newest software releases found that the computer reports him having half the memory he had before. He started to dig into it, and found threads like this. Lots of people are having this problem and Apple hasn’t officially acknowledged it. Apparently there were a number of discussions on the apple forums but they were shut down by moderators. This could be a class action lawsuit if it gets out of hand.