For the last couple of days, a really annoying popup has made Google Photos almost unusable, and I can't make it go away. It is four screens of stuff about what Google Photos can do, at it appears immediately when I open Photos, and I have to click through all four screens before I can see or do anything. And then it reappears anytime I click on a photo or try to do anything else. There is no apparent way to close it or to stop it from continually happening. This makes Photos impossible to use, as a practical matter. Why is this happening and how do I stop it? I contacted Google, who said it was a browser problem. Apparently it is, as this does not happen with Safari.