TL;DR VERSION:
I was browsing the internet and closed all of my tabs on accident, upon restart I received this security warning...

i've gotten it before but now it's appearing on every site I go to like 20 times in a row. Is there any way I can stop this? Thank you.
One find day I was browsing the fine interwebs, looking at some fine youtube videos and everything was just fine, but then my mouse freaked out and I accidently closed out every tab I had open at once. This isn't the first time this has happened so I didn't really care (as I am a bit of a spaz sometimes). However, upon re-opening all of my tabs...
THIS...
Began to spam my screen, I've gotten this message before, and typically it's not very bothersome, but as of now, every web page I click on brings up like 10 or 20 of these windows and I can't finish closing out one before another one comes up. We'll take youtube as an example. I open youtube and the warnings pop up, I get them closed and everything is fine, but then I search for a video and they all show up on the results page next! This has never happened to me this badly before, and I would like to get rid of it. I run the "Opera" web browser and use Windows 7 if that helps.
Any help is much appreciated. Thank you for reading