I've been posting and working through all the options throughout this week including the intermediate performance driver update for ATI and several differenct Steam startup settings and rageconfig.cfg files. I undid all of those changes, uninstalled the Performance driver, rebooted, reinstalled the 11.10 driver and have been able to run the game for several hours without a single failure to load an area. I have some slight delay in textures appearing but I will take the suggestion to disable Driver level Antistrophic filtering and will use the game startup option to enable AF. I have a I7 - 960 3.2Ghz, 6 Gb Ram, 5870 with essentially default settings.

I have entered 5 areas I was previously locked out of. I am slightly past Wellspring and spent most of my time today clearing out areas I was previously unable to enter.
It's a shame this happened but it seems to be headed in the right direction.
Old

After the new RAGE patch was released I removed all video card/ driver level settings that were not "Allow Application Control" I installed the patch with 8x AF and using LARGE Textures. If the video card setting did not have an "Application Controls" option I left it at default.

The game played through several missions smoothly and the texture details are noticeably clearer. No crashes in an addition coupld of 4 hour sessions. All is looking good. Good luck.