Vivaldi won't work.
I have tried to use Vivaldi browser on my computer but i always run in the same problem. After using it for a while the browser closes and i won't start again. If i reinstall the browser it works for a short time, but then it stops working again. I have tried to run it as a administrator and i also checked that it is whitelisted in Norton 360, but nothing seems to work. It is really a pity because i really liked the browser but i feel quite helpless now and i don't know what to do anymore.
@JussiR: Though whitelisted, Norton 360 may still be killing it. 3rd party security has such a history of causing more problems than it prevents, I no longer run it on any of my machines. One of the problems with even the "good" companies is that everything is automated, and they can't keep up with new programs, to allow for them in their automated routines. So software they've not heard of may be blocked by their "security" measures, and it may take months (or never) for them to catch on and correct it. Then, too, all such "security" software gets its fingers into EVERYTHING your computer does, consumes RAM and processor cycles and adds execution steps, thereby slowing down your machine. Every machine running effective 3P security runs slower than any machine of the same specs, not running it.
I used to be addicted to AV's and HIPS-type programs for a good 15 years or so, but I've sworn off them for the past five years. Instead, I rely on built-in OS security, a physical firewall (in my router) and safe/smart browsing practices. That has kept me safe. If you can't keep from clicking on things you know nothing about but that "look interesting," or you click on links in emails from unknown sources (including ones that LOOK like they're from a trusted source, but aren't) that might not work for you.
It's POSSIBLE you could run them both, but you'd probably have to go through and whitelist all of the Vivaldi programs - "Browser," "APP:Vivaldi," "Vivaldi Helper," "GPU Process," "Background Page:Vivaldi," "APP:Vivaldi-extension" (possibly for each extension), etc. - to ensure there's nothing that Norton isn't killing.