Gifting of The Witcher 3: Wild Hunt temporarily unavailable (fix in progress)
Due to a very large number of fraudulent transactions coming in, we have had to disable the gifting option for three items: The Witcher 3: Wild Hunt, The Witcher 3: Wild Hunt Expansion Pass, and The Witcher 3: Wild Hunt - Game + Expansion Pass.
We are working to clarify the problem and prevent further fraudulent transactions from being made.
We will make gifting possible once more as soon as this issue is resolved.
Windows Vista uses functionality called UAC (User Account Control) which, among other things, scans executable files before launching them. This may cause the installer to be launched after a long delay, depending on its size (sometimes many minutes). You can bypass or disable UAC for the duration of the installation process to bypass this delay.
It is generally advisable to disable UAC altogether, as it is known to cause problems in some software, especially games, both old and new.
To disable UAC, please consult this support article.
You could also try launching the installer by right-clicking the setup file and selecting "Run as Administrator".
Finally, if your installer is divided into multiple files, make sure that you're trying to open the executable file (with an .exe extension and an orange icon) rather than a .bin file. The .bin files aren't disc image files, but archives used by the executable file.