Centos 7.5..and My GDM Greeter/GDM Don't Work Anymore

So, we've updated to 7.5, and for two machines--A Dell Precision M4800,
and a Dell Precision 7510..both running Radeon cards--we no longer get
the GDM Greeter login box NOR can we switch to virtual text login
terminals. It's been driving me nuts. The systems do allow for SSH
logins, so that's how we get to them, but I've checked the Xorg.0.log
and nothing stands out. Did a systemctl status gdm.service and got this: