I've been mining for a few days now and when I first started out, I couldn't submit any shares because it always returns a "Verification failed, check hardware!" warning.
I did some googling and it seems to be a common problem. I tried everything to no avail until I tried mining with Phoenix 1.7.5. Smooth as silk.
I'm not sure what's the difference between Phoenix and the other miners. Some enlightenment, anyone?