Hi there, I have similar problem with CGMiner and "error -5: Enqueueing kernel onto command queue gpu0 failure, disabling!" (in mine case for two GPUs without crossfire). This seems to have happened since I tried to use "setx GPU_MAX_ALLOC_PERCENT 100" in Windows in order to increase the maximum thread concurrency. Greek, did you modify this value as well?

I tried to delete the registry keys for GPU_MAX_ALLOC_PERCENT but it didn't help. Now CGMiner is always showing this and stops when I try to mine litecoin. Bitcoin mining works fine though.

I tried reaper as well but it didn't work even with 6144 thread concurrency. I also tried GUI Scrypt miner which appears to be based on CGMiner as well and it works fine with 8192 for thread concurrency.

I am using Windows 7 Ultimate x86_64 and tested it with cgminer 3.0 and 3.1 (reaper was the latest version) but no difference. Does anyone know how to fix this?