The release notes for CentOS 6.4 state as follows:
With this release the ABI for the X.org video drivers changes, possibly resulting in a failing X-Session. If you are running 3rd party drivers - i.e. vBox addons, nVidia, ATI or ELRepo - you need to ensure a compatible driver is loaded.
I use flgrx from ELRepo. Does this mean that fglrx is now incompatible with CentOS?
Yves Bellefeuille