I recently installed Windows 8 preview edition, but it got buggy and now I want to install Windows 7 again. I have Windows 7 on cd, but on Norwegian. I have installed my Windows 8 in English. So when I try to install my Windows 7 with cd it says: You can not upgrade/install a new os with another language that my Windows is installed with? What to do?
Are you booting from the Windows DVD or are you just trying to run the install program from within your existing system? I think you're going to need to do a fresh install by booting directly from the DVD itself.