YAY! Last night I was able to get everything shut everything down and roll back the NVIDIA drivers.
Who'da thunk it, but NVIDIA's driver was causing the issue! Rolled 390.48 back to 390.42 and everything started working quite nicely.

I *KNEW* I should have rolled back the driver before posting.

I'm probably going to get scolded by not creating a new thread and for that, and if that's the case, I apologize ahead of time, but I'm experiencing a similar issue. I'm running in 24-bit color. CentOS 7 (with the GLIB 1.18 fix as posted in a previous forum) and things were working quite well until ...