This started to happen suddenly, without me doing anything. I didn't browse a specific site, just had 3 tabs open with sites I usually visit. And I get a crash report:

A problem has occurred, forcing Opera to close. To help us avoid similar problems in the future, please send an error report below

If I choose "Full restart" from that dialog, it restarts and crashes again immediately. The same thing happens if I choose "minimal restart".

What could be the problem?

I guess uninstalling and reinstalling would fix it, but I don't want to loose current settings, emails, cookies etc.