Ok so this happens when i watch Youtube videos, or my bf watches them. Randomly a pop-up pops up and i can't see what it says as it disappears right away. After it popped up, youtube videos say plug-in fail and i have to restart Safari in order to watch youtube videos again. I only know that the pop-up has a yellow error triangle icon on it...it has popped up about 10-15 times and i can never see what it says. It pops up really random times and it is very annoying, what to do?