Hi Dax, I answered you last post.
It will because you have your settings in internet security set to high.
Set it to medium if the case.
It will happen if you have windows, security center or essentials installed if running windows 7 or 8.
If the system is not yours, or it is used by another person.
Not home use then an admin of the system may of disabled features to download and install programs as a safe guard.
In such a case you would have to talk to an admin to set your privileges or user rights to be able to do this.
Or any install will simply quit, based on what the admin setup as user rights for your account, if the system is used in an office ect and not your own.
It`s used to stop other users form installing software that may contain a virus or doing system changes that could impair the system.
May I ask what browser you are using ?
If your own system simply lower the internet security settings.