First off, this is a semi cross-post from the AMD Game forums: http://forums.amd.com/game/messageview.cfm?catid=279&threadid=153525&enterthread=y
There has been an ongoing series of problems with the Catalyst 11 series drivers and the OpenGL based game City of Heroes, generally starting for most players around Catalyst 11.5, but with other players expirencing problems across Catalyst 11.3 and 11.4.
I've been able to reproduce many of the reported stability problems under Linux with Transgaming's Game Tree Linux Translation layer, indicating that the problem seems to be with the driver itself.
As of right now the ongoing error continues in the newly released OpenGL 4.2 beta driver. I pulled the error reports taken under Microsoft Windows Operating System Version 7 X86-64, as well as ran a GPUZ logging of my AMD card's sensors:
I don't know if these logs will help effect a solution for this game, but I'm not sure where else to start in poking AMD to fix these problems.