KDE plasma desktop totally failed; can't log on

[Temlakos]

Everyone:

Has anyone had a problem like this?

For the past several weeks, one of my two F22-KDE machines (a Dell 
Inspiron 1200 running F22 in the KDE spin) has been freezing up while 
trying to bring up Plasma and two auto-starting applications. Eventually 
I could get to a good session, but only after having to log out and log 
back in once or twice. And sometimes the system would freeze up for no 
good reason, and I would have to do a hard shutdown--holding down the 
power button for five seconds.

Yesterday, during the most recent big update push (160+ packages), that 
system froze up in the middle of the update. I have no idea what it was 
trying to do at the time. I do know it failed to install the latest kernel.

I then used the power button to force a shutdown.

Ever since then, whenever I try to boot that system, it will boot, all 
right--to the last kernel before the new one. I get to a login screen. 
But when I try to log in to a Plasma desktop session, I get a brief 
message, too brief to read. And then the login screen returns. Result: I 
cannot start a Plasma desktop session.

But: if I designate the Session Type as a Failsafe session, I can get 
in. I then arrive at a command prompt.

Now that would let me do something. I want to know what.

And I wouldn't even know what logs you'd need to see--nor how to get 
them off that system and onto a system that can send e-mail.

In sum: I think I can rescue that system. I just don't know how to do 
it, once I log in to a command prompt.

Temlakos