thanks for taking the time to reply.

i use batch files with and without the GPU ALLOCATION command; both cause the no-response outcome i mentioned in my post.

another confounding problem is that sometimes CGW won't launch the mining exe either. this happens with different profiles pointing to cgminer.exe, sgminer.exe and vertminer.exe, and correct config files and arguments (eg the keccak and scrypt arguments). it doesn't seem to be a pool issue as the miners don't actually launch so they don't get as far as trying to log in to the pools. it also doesn't seem to be related to GPU overheating, as CGW shows the temp is well below the auto shutdown target temp. so it seems random.

has anyone else experienced this?