@belkaspeleo Yes, it seems that there's something in the online account, maybe some old settings or something else that creates some kind of conflict. In fact if you create a new account at the end of the day you'll put the exact same things you had in the old one (bookmarks, settings, passwords, etc.) as it's what you have saved in local and that obviously were mirrored online, but somehow it will work flawlessly. However when it freezes it seems to repair the account too and it will solve the problem.

This is a problem I have on three computers, I am not sure it's opera, but it's the only software I use on all my PCs, and my colleagues that uses really similar PCs with the same software (same programs, same drivers, except opera) don't have this problem. What happens is rather difficult to explain: something stops working under the hood, but you may not notice it straight away, for the most part you can finish the task, but as soon you try to do something else you get stuck. So you may be able to work with a program, and even save, but when you want to close it it freezes. I generally can open the task manager, but it can't kill anything from it, and if I try rebooting or powering off it doesn't do anything (with right click on the start button, as the start menu doesn't generally seem to work). One thing I noticed every time is that the clock stopped, and sometimes it's stuck something around 5-10 minutes back when I notice that the computer behave strangely. The only time I noticed it happening in real time it was yesterday when I was watching a youtube video, the image got stuck, while the audio was continuing as normal.
This problem happens me not that often, probably around once a month, not a big deal but still annoying when it happens. So my question is, am I the only one that has this problem?

@belkaspeleo Yes, it seems that there's something in the online account, maybe some old settings or something else that creates some kind of conflict. In fact if you create a new account at the end of the day you'll put the exact same things you had in the old one (bookmarks, settings, passwords, etc.) as it's what you have saved in local and that obviously were mirrored online, but somehow it will work flawlessly. However when it freezes it seems to repair the account too and it will solve the problem.

@belkaspeleo
That happened to me too with that same version. I solved just waiting a couple of minutes (but depending on your pc it could take even half an hour), even if windows says that the program does not respond keep it open. If it doesn't work you have to opt out from syncing, but you'll need to disconnect from internet first to keep opera open. After that you can create a new account and sync all your old stuff from local to that new account, that is like making a clone that works again.

@mquigggeorgia
I didn't know that, I tried and it works! Windows told me opera didn't respond and asked me a few times if I wanted to close it, but after a couple of minutes everything is working fine! Thank you for the tip!

I had the same problem today with version 69.0.3686.77. As I understand the problem is in the account online. To make it work again you have to disconnect your pc from internet, so that opera can stay open for more than a few seconds, go to settings and disconnect from your account. After that you can reconnect, everything will work (except for sync...). If I try to log in again it will freeze again, but after I created a new account the sync seems to work fine with that one.
I also had the same problem back in march when the opera version with workspaces came out (it should have been the 67), and in a couple of minor versions the problem was solved. My hope is that it won't happen cyclically every couple of months!