The driver needs an update. Hang in there until it's updated or fall back to 10.8.4.
BTW, we didn't see this problem with the development builds.
Just got mine working I used:
http://sourceforge.net/projects/genericusbxhci/files/Snapshots/
Downloaded: GenericUSBXHCI_1.2.6d1.tar.gz
And used this command:
tar xvf GenericUSBXHCI_1.2.6d1.tar.gz
sudo chown -R 0:0 GenericUSBXHCI.kext
SLE=/System/Library/Extensions
sudo /bin/rm -rf $SLE/GenericUSBXHCI.kext
sudo /bin/mv GenericUSBXHCI.kext $SLE
sudo kextcache -system-caches
sudo kextcache -system-prelinked-kernel