I would suggest downloading Windows 7, then doing an in-place upgrade which will keep your files but reinstall parts Windows itself. It won't take long (maybe up to an hour).
http://www.pcworld.com/article/243190/how_to_repair_a_corrupt_windows_7_installation.html
Wish I could help, but I think u might get help from windows live chat.
Buy a new computer, all problems solved.
Will try out later.
Probably what I'm going forWhat about USB installation?
