CS3 installer fails in win10 because of Flash Player version

Hello, everyone.

I have a CS3 license and I've been working with it for 10 years. Suddenly, this week, I started to have that issue of not validating the license and the need of re-install it with the new installer, with a new serial number.

The problem is that the serial number validator is not working (it keeps saying that the number is invaild - even I using it all those years), so I can't download the new installer, neither use a new serial number.

Just as a test, I managed to install the Suite in a Windows 7 SP2, even using the old installer, and it went fine ("Never Register" and all). But now I'm using Windows 10, and it seems that the main issue is that Win10 has Flash Player embedded. When the old installer tries to install any program from the CS3, it also installs the "shared components", which includes Flash Player 9. So, the install fails and the Windows Event Log shows that it breaks because Windows already has a later version of Flash Player (c:\ windows/sysWOW64/macromed/blablablabla... failed to register HRESULT - 214722473).

I tried to remove it manually, change regedit, install flash 9 manually, but none of these really worked.

I don't know what to do, since my legit license is not validated by Adobe anymore (so I can't get the new installer) and I can't even try to re-install it again in Windows 10 because of this Flash issue.

Any (ANY!) help will be much appreciated. Thanks.