Did you install the ATI drivers from ATI or as an RPM? If so that "might" be the culprit. Did you use
THIS howto to install? If not you may want to run, logged in as root:
Code:
# ldconfig
# aticonfig --initial --input=/etc/X11/xorg.conf
# sax2 -r -m 0=fglrx
BTW, the # symbol just means the root prompt, don't type it in.
HTH,
MMYoung