Thanks gnar1ta$ for the suggestion - it worked!  Now I'm experiencing another problem: OpenCL won't recognize my GPUs; only the CPU shows up when I run clinfo.  I have agreed to the icd license and even downloaded and extracted the icd-registration file again just in case, but it made no difference.  Would reinstalling the SDK help?

(I have posted a similar question on the Smartcoin thread but it seems more appropriate here; sorry for the seeming double-post.)