For some reason, when I log in KDE does not start, though KDM starts just fine. I am able to get into IceWm just fine, so the issue seems to be wth KDE itself. I ran a zypper dup just to make sure I have the latest packages but this does not seem to have solved the issue.
After that messy upgrade yesterday, including KDE and upgrade/downgrades, have you tried backing up the hidden .kde4 settings file then deleting it (outside of KDE) and rebooting? KDE will then generate a new file on start up. I am going to do that for mine, even without your problem, as a precaution.
My plan worked, BTW. I was able to get into KDE after making the install more “vanilla.” The only repositories I had enabled were the openSUSE current. (This is good, BTW, being able to revert is a really powerful troubleshooting tool!)
Then I ran sudo zypper dup --from Tumbleweed and I got the same error as yesterday. Since today my bravery is reckless, I ran sudo zypper dup and shut down my machine after-wards. Well, I was able to get back into my desktop using KDE 4.11! For some reason my login theme is Elarun. :\ not a big issue, though, I can change it later.
Yes, that problem is on the Factory mailing list now, but no real solution (nor a response from Greg K-H there yet). Interestingly one post said that Solution 4 (IIRC the one you took) was the best looking option. So my choice of Solution 2 not so good, and I see today that Kontact and its children won’t start. I’m not too bothered as I only use Tw as my test system. I’m sure that was caused by yesterday’s fiasco.
About a week back when I first installed Tw on my 12.3, I got a different login theme as zypper dup removed some branding - probably the one you call Elarun - and thought it was ok. But yesterday, choosing Solution 2, it went back to the openSUSE theme (I saw te branding packages being added) and still is after today’s update.