Did you do a proper reconfigure of xorg.conf?
sudo aticonfig --adapter=all -f --initial
Did you export your display variable after xorg is started before mining?
export DISPLAY=:0
I could have sworn I did the first command, but I went ahead and did it again and rebooted. I was forgetting to export the display variable; after doing so, everything (except for AMDOverdriveCtrl) is working wonderfully! Thank you!