@erg I have the same problem. After more than a year of using Opera with no major problems. It suddenly started giving me a "too many redirects" not only for gmail but other sites as well. I deleted 4 weeks worth of cookies and it cleared up for a few days, then happened again. I deleted one weeks worth of cookies from the Opera settings menu. That worked for a day or two. Then it froze completely. When I try to load any site, it just spins away and never reaches the site, then when I tried to go to Opera settings page it just gave me a blank page. I closed all the Opera windows. Then I tried to restart Opera by clicking the Opera button on the bottom of my screen, but now Opera won't start up at all.
It seems that other people are having similar problems.