I recently upgraded to Ubuntu 21.04 from Ubuntu 20.10. I already had programs installed that I kept with the upgrade. Subsequently, I then installed BOINC Manager and the associated client software. I used the command line: sudo /etc/init.d/boinc-client start to start the client for BOINC. I then connected to my Einstein@Home account using BOINC Manager. The packages loaded as usual. I started the screen saver (rotating astronomy sphere). Then within a couple of minutes my entire computer system freezes.

I have tested my various other installed programs for astronomy and they all work just fine and do not freeze my system.

My system is as follows

Intel® Core™ i7-4500U CPU @ 1.80GHz × 4
7.7 GiB Memory
Intel® HD Graphics 4400 (HSW GT2)
1.0 TB HD

Ubuntu 21.04
64-bit
GNOME Version 3.38.5
Windowing System Wayland

To check the version of BOINC Manager I had to start the the program which froze my system before I could add the following:
BOINC Manager
Version 7.16.6 (x64)
wxWidgets 3.0.5

I started the screen saver (rotating astronomy sphere). Then within a couple of minutes my entire computer system freezes.

Do you have time to stop the screensaver before it freezes to see if that is relevant? I would also try reducing the number of running tasks if that is possible before freezing and if you can stop computing completely check the event log after doing so to see if there is anything in there. The other thing that might help is upping your ram. 8GB before the motherboard steals some for video is a bit low for four cores with many projects these days.

He said his problem is fixed once he changed back to X.org WDM that I advised him to do.