This just happened to me.
Like a lot of people, I don’t have Flash installed on Safari (I use Chrome when I need it). This website tried to popup some kind of Flash interstitial or overlay and because I didn’t have Flash, it just froze the entire page, making it impossible for me to read the contents or even see other ads.
If you’re going to use Flash ads, you need to have non-Flash fallbacks. That’s at a minimum, otherwise you’re either not serving ads to a lot of users, or you’re going to just crash your Web page and force people to leave.
I would strongly discourage you, however, from using Flash. Most mobile devices don’t support Flash (including the iPhone and iPad) and more and more desktop users are no longer using it. Flash has been so problematic that Firefox recently blocked it by default. If you’re a news org, you may have less than half of your user sessions from devices that support Flash. That’s in 2015. Give it a few years and that number will continue to drop dramatically.
The University Herald website is bejeweled in all manners of ads, so there are bound to be issues for a lot of users.