Using ubuntu, and sometimes it freezes and crashes, how I fixed it

One my operation systems is ubuntu.
sometimes it freezes and crashes.
And I found that most of the time, the browsers freeze. I used firefox and chrome.
And I look for some other browsers. And I found opera and chromium.
I tried to install opera.
I downloaded opera deb file. And tried to install deb.
I tried the command first:

sudo apt install ...deb

not working

Then I tried sudo dpkg -i xxx.deb

works.



finally installed opera. now it seems no crashes or freezes

Opera seems stable. But it does not support some videos.

To install chromium, I used
sudo apt install -y chromium-browser

And I installed it. chromium seems not so stable as opera.