Well, I think I finally figured out why my Opera adblocker was enabling itself at random. I have a program called Advanced System Care which I run regularly when it tells me to which was causing the trouble. If I run this program and then open Opera the adblocker is enabled. If I don't run this program and open Opera the adblocker isn't enabled so there is a conflict for some reason. It was a random thing because I ran the program at different times when I wasn't using Opera.