I just updated to Mavericks from 10.8.5 on my 17" late 2011 MacBook Pro, 16Gb RAM. Prior to updating I was able to use my Magma 4-slot PCI (not PCIe) chassis via their ExpressCard 34 card. After updating, the chassis or the card are not recognized. The card doesn't show up in about this mac, system information under PCI cards. The icon for the ExpressCard does show up in the MenuBar, and greyed out it says PCI-to-PCI bridge, hinting that it indeed recognized the card. Unfortunately, it does not. I have read in Apple forums, and there is a thread here too, that other users are having problems with SSD ExpressCards and other ExpressCards. Did Mavericks stopped supporting ExpressCards altogether? Is anyone else having problems with their ExpressCards? If anyone knows of a way of bringing back that functionality, perhaps by recovering a kext file or some other way, please post.