I'm having this same problem, but just for the past week or so. I'm using a 1-year-old iMac. It never happened before, and now it happens nearly every time I try to open a link from an email. If the solution is to use Safari, that's really not ideal. There are many good reasons why I use Chrome as my default browser. There has to be a better solution than using Safari. Sometimes it clears up if I restart my computer, but that's also not the best solution. If it's only been happening for the past week, something is wrong that I hope Apple will fix.