If you are using one of these you will have to disable them or set the Technic Launcher as an exception in order to install it. They block it by default since they don't recognize it (of course). If that doesn't work, uninstall those terrible anti-virus programs and get one that doesn't get in your way constantly. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.