I'm having the same problem. The PDFs won't load, and the .zip files aren't working. When I click on the link to download the .zip it takes me back the the download page. The weird thing is the .zip for book 1 worked just fine (at home and at work), but not any of the others /shrug
When I did it home it worked fine, but not here at work. I use Firefox at home but the computers here have Internet Explorer.