Looks like you are on Windows; what web browser do you use?
Try downloading the offline installer from http://helpx.adobe.com/content/help/en/flash-player/kb/installation-problems-flash-player- windows.html#main-pars_header and save it to disk, then close all browser windows and run the downloaded installer.
[topic moved to Flash Player forum]
I think this is problem with the browser. Remove your browser then reinstall it. Please don't overuse the browser plugins or add-ons as they create confilict problem with browser and addons and both don't work properly.