Did you format the drive? You cannot "downgrade", you must wipe the drive and then fresh install Win 7.
I have not gotten to the point of formatting the drive.
I have tried the install 2 ways:
1) Running in setup in Win8, selecting drive C, then the system resets and tries to install and freezes
2) Booting from DVD first, tries to install files, and then freezes
Both hang at the same point. Starting Windows