About 2 months ago I installed Ubuntu GNOME 16.04. About 1 month after using it without any problems I started suffering from sudden crashes. Everything freezes but the cursor works and the internet connection (streaming from twitch) and audio (can still hear twitch audio) works. Can't enter TTY either. I just have to reboot from hardware button. I had used Xubuntu for almost 2 years without such problems, and Windows10 works just fine.
The day this started happening I had removed 1 GNOME extension with rm rf ~/blabla/extension because it wasn't working and couldn't be removed normally. The extension was the system-monitor. I would think this has nothing to do with it.
/var/log/syslog part from around a crash I had earlier: https://pastebin.com/5LvZ8qX5
There is nothing on /var/log/kern.log from the time that a crash happened.
How do I diagnose what's wrong? (Tried to look for duplicates here, didn't find similar symptoms)
SOLVED: I was using Nouveau drivers, the default ones. I changed to nvidia proprietary drivers I downloaded from the website (.run file) and now it works.
So there is obviously a problem with the combination of GNOME(?)+NVIDIA GTX660 (other models?)+Nouveau
If you are facing the same problem, use nvidia proprietary drivers.