Not fully secure and strange popup

Hi, logged in 12.05 pm Sunday morning, very slow loading. While waiting for forum to load, received a popup asking me to draw a circle or rectangle and watch it be turned into a Valentine's heart. Killed that off and waited another 30 secs and the forum loaded with a warning symbol (solid triangle with exclamation mark inside) appeared in place of the normal padlock security symbol on the address line. Pointed to that with trackpad and it opened a dropdown suggesting the site was not totally secure. Padlock has returned as I type this. Opened a new window and loaded a new forum session, loaded much quicker but warning triangle remained while the Forum front page was on screen, but no popup.

Dell XPS 15 (I7, 32GB) Win 10 home, Opera browser.

Mal