Tech. support: http://emailcustomercare.amd.com
New forum for issues related to Steam: http://devgurus.amd.com/community/steam-linux
Feedback form: http://www.amd.com/us/LinuxCrewSurvey
Don't forget to attach /usr/share/fglrx/atigetsysteminfo.sh report.
So what status of issues you submitted in current driver? I mean does it still reproducible in Catalyst 12.10-12.11?
This bug was submitted to nVidia tech. support in August, but in 313 driver release still doesn't fixed.