The guy who made the miner included my fix for later drivers in github, but never made a new Windows release. Fortunately, it doesn't require a recompile. Simply download this file: https://raw.githubusercontent.com/djm34/sgminer/master/kernel/bmw256.cl - and replace bmw256.cl in the kernel directory with it, then delete all files ending in .bin and try again............

this may be the answer to your problem, it helped me!