Yeah, I don't think that Windows 8 is the problem. By description it seems like a combination of faulty downloading and internet connection problems. The fact that it seems like an internet problem to me may be because not every thing is there. Just go in the minecraft folder and make sure every thing is there. You may need to delete the whole minecraft folder. (you probably know this but this is how you get to the appdata in windows, here's the link: http://windows8themes.org/how-to-view-a ... ows-8.html )
