Well, that is certainly nice to know! Sure would have saved me some time if it had been outlined in the manual or simply printed out as "GPU Error Rate"
After significantly lowering my config values, now I seem to actually be processing work!
Had a similar issue myself when getting started with gpu mining on my NVidia GT555M, had to bring down the GPU thread concurrency down from 6144 down to 2048 initially to get it hashing properly and then steadily got up to 4096 where its at now, though the stale share count is pretty high on gpu mining (between 40-50%)..
This is apparently linked to the number of shaders and the thread queue depth for each shader - the shader count is woefully low on NVidia GPUs - mine is 192. Wondering if the magic number is 192 shaders multiplied by sharethreads 18 = 3456? Will have a stab at this to see if it helps..