Ubuntu Mate 16.04 for the Raspberry pi 3 keep FREEZING!

Despite updating the software for patches.

I still encounter that the Raspberry pi 3 keep Freezing … that rendered my mouse and keyboard not to response to move over the screen and the whole entire OS just FREEZE.

I have to manual un plug my power cord to reboot.

I had a similar problem and the answer here might help.
Basically you should try to kill the corresponding process that is blocking the system instead of pulling the power plug. Your file system might be faulty. This can happen easily when you don’t properly shutdown Ubuntu. See also here .
So try to press ALT + CTRL + F2 and see if you can do something on the terminal to find out which process is causing this. You might very well find out soon whether or not your file system is corrupt.
I did replace my SD-Card with a new one and up until now the situation got better for me.

Hi, sorry for reheating old topic but recently I had similar issue.
My Raspberry Pi 4 model b with 4 Gb Ram got freezes after some periods of time on Ubuntu MATE 20.04
Only mouse pointer was movable and keyboard was mostly unresponsive.
I got it unfrozen by
pressing Ctrl + Alt + F1, then press enter,
enter login and password,
enter 'htop' command,
press F5 for tree view,
with down key find process called xfce4-screensaver,
press F9,
select 15 SIGTERM, press enter.
After that press 'q' to exit htop, press Ctrl + Alt + F7 to comeback to graphical environment.
Hope that help somebody