I have a Windows PC, and have used iCloud Photo Stream for a while. A few months ago, the streams just stopped appearing. I have logged out, then back into iCloud. I have changed the folders to be used for Photo Streams. But, no matter what I do, I can no longer get streaming on my Windows PC. The streaming between my iPhone and iPad works fine. I suspect that this tool place with a recent upgrade of either iTunes or iCloud, but this problem has been with me for six months or longer, and I would have expected others to have had the same problem (so that it could be fixed).