Approximately once every 1 to 3 days of uptime, the system experiences a sudden
and inexplicable crash: The image completely freezes in place, although unlike
similar crashes in the past I can keep moving the mouse pointer around. A few
seconds afterward, I find myself in a black console... and a few seconds after
that, I'm back at the login screen. If I attempt to log back in however, the
image either freezes again or desktop effects are no longer working without any
error message as to why. Not even forcefully restarting X11 (control + alt +
backspace twice) fixes the remaining glitches, and the only way to truly
recover the system is to also reboot.

Although the crashes are completely random, I vaguely get the impression they
might be happening when an event triggers certain desktop effects. Several
times the crash occurred as a system tray notification popped up, whereas just
now the system crashed while I was switching desktops in the middle of the
desktop cube animation. Certain games might also have a probability of causing
this.

I use the free video drivers and default system packages, all latest versions
of openSUSE Tumbleweed. My card is a Radeon R7 370, GCN 1.0 on RadeonSI.