Hi Guys
A few important points.
If you are reinstalling you must use a registry cleaner and afterwards reboot your system.
Make sure you uninstall from the control panel both SH5 and Game Launcher.
Do not install in the default program (X86) folder.
When the installation has completed do this:
Post #5 Just Finished Installing SH5 > Do This Now
You are quite likely to see a windows error when the game launcher updates.
Post #173 Ubisoft Game Launcher How To Fix It
When you change the game launcher to run as administrator the game should automatically start.
Run all your applications in administrator mode.
SH5 whether you are using a dvd or download is linked for life to your system along with your email address and Uplay password.
If you want to replace your SH5 at any time to your existing system you will need the SH5 key a new email address and new Uplay password.
Peter