Gnome keeps logging me out - screen res?

[jwood]

I recently put OpenBSD 6.3 on an old Dell Optiplez GX620 (4G memory) with a ViewSonic LCD screen. There were no problems with the install or in basic Xenodm mode. Gnome does not work, however. I can log in , but when I run an app or place the cursor in Terminal, Gnome goes black, probably crashes and then takes me back to the login screen (meaning, I assume, that is it has restarted. I believe there is a conflict over screen resolution or refresh rate between the computer and monitor. Despite over a dozen attempts, I cannot change the screen res from the settings utility inside Gnome; that’s one of the things that causes a crash. When I viewed /var/log/Xorg.0.log.old, there were multiple Modelines that seemed to list every resolution I tried, usually with two or more refresh rates. At the end it said:

160.241] (II) intel(0): resizing framebuffer to 1600x1200
160.241] (II) intel(0): switch to mode 1600x1200@60.0 on VGA using
pipe 0, position (0, 0), rotation normal, reflection none

1600x1200 is the resolution that OpenBSD set when I installed Gnome, and it’s the one that keeps crashing.

When I try to change the screen res from within Gnome, I get a list of possible resolutions, but when I pick one, the screen flickers black and when it comes back, the Displays tab is grayed out and will not let me change off of 1600x1200. When I run Firefox, or try to put a cursor in Terminal, it crashes again.
Is there a configuration file where I can set the Gnome screen res using nano in CLI mode? Where in the directory structure is it?
Also, is my real problem that I’m using a cheap old LCD monitor and need to buy a new one?