I upgraded to Windows 10 a week ago (August 13, 2015). I did the ''rollback'' to Windows 7 the same day. Now my license is invalid. No way to contact Microsoft other than have them call me back yesterday evening (a full week after seeking help). They could not help me because I misplaced my _legal_ retail DVD installer. They say the Key in my computer's registry is ''blocked'' and they cannot unblock it. They admitted that the key in the registry is not always the same as the key on the disc (even though I originally used the key on the disc to validate the Windows 7 installation in the first place). Again, they (a supervisor) admitted it is not uncommon to have a _different_ key in the registry after validation with the retail key. They told me if I find the install DVD, and the key is different than what is in my registry, they ''may'' be able to re-validate that keycode if it is declined by their auto-validate system. // In short, the Windows 10 update trashed my Windows 7 validation, and now because I cannot find the retail disc with the key on it, I am screwed. // Note: This was an older Gateway all-in-one computer. Ironically, my other _newer_ Gateway all-in-one (2 years old) failed to update to Windows 10. After reboot, it said ''resetting back...'' and after it finished I had Windows 7 back, but now that computer has a trashed Windows Updater (all updates now fail to install). I followed all advice by Microsoft (and later also tried ''fixes'' found at various forums), including the Microsoft update ''fixer'' and ''re-installer.'' Nada, nada, nada.... // NOTE: Granted, it is my problem that I cannot find the installation DVD with the key, but the fact remains that I had a computer with a valid key code that had been acknowledged by Microsoft as ''genuine'' for the past 3 years, and after upgrading to Windows 10, and then deciding to ''rollback'' to Windows 7, my validation was trashed. These are facts, regardless of my current inability to locate my retail DVD and key code.