^@^@^@^@^@^@^ on black screen and then crash?

Desktop Environments Gnome
1

It seems random but mostly when I tried to launch something or open a new thing, the screen becomes black and show something like

^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^

for a second and the the login screen appears. Of course, if I log in, all the previously running applications are gone.

Has anyone experienced this before? Why does it happening, lack of system RAM?

2

Your display server crashed.

If you would be so kind to post your journal entries, that would be great and, I suspect, even productive.