Photostream not working in Windows 8 64-bit. Photostreamdownloader.exe using an entire CPU core.

I have been trying to get iCloud Control Panel and Photostreams working on my PC, but no photos download from iCloud. I can see that the Photo Stream folder was created, but it stays empty - photos never download. If I open up the task manager while iCloud is signed in, I can see that "PhotoStreamsDownloader.exe" is using 100% of a CPU core and appears to be doing nothing. No photos ever download. I found some threads of other people having this problem, but there was never a solution that worked for everyone. Some people reinstalled, some deleted all pics from their photostream... I've tried every suggestion I can find but I cannot get photos to download. The only way I can get it to partially work is if I set "photostreamsdownloader" to Windows 98 compatibility mode. Running it as an administrator doesn't work either. Does anyone know how to fix this.