[CentOS] Trying again: KDE fails with a gray screen after login, can't reinstall

I set for graphical mode, I get the login screen, I change to KDE, and 
the screen goes black, then after minutes, gray with a cursor, and 
that's it - I left it overnight, no change.

Brand new install (as of yesterday). Missed any "agree to license", and 
missed choosing software. Manually groupinstalled
Installed Environment Groups:
    KDE Plasma Workspaces
    Development and Creative Workstation

Tried to reinstall:
No group named KDE Plasma Workspaces exists

I'm assuming I need to install something else, but does anyone have a 
clue? I really do NOT want gnome.

	mark