My friend is trying to bring his Windows Vista down to Windows XP. When he inserts the disc, a little box appears that says "Run setup.exe", or "Open folder to view files". He clicks "Run Setup.exe", the Windows XP installation menu opens up. He clicks on "Install", and then it freezes for a bit, then nothing happens. Any idea as to why this is happening? (If it's any consolation, it IS a burnt copy.) Thanks in advance.