Raoul,
I'm pretty sure you're having the same problems I'm having, here's a copy of an email from a guy named Peter Nome:
Problem narrowed down: the culprit is {kdelibs kdelibs-bin kdelibs-data kdelibs4} version 3.1.4-3.
Downgrading to 3.1.4-2 fixes the problem.
I'm getting "KThemeStyle cache seems corrupt!" while kde is loading, and if I start kde with an empty .kde, I get an incomplete selection of themes (e.g. no Keramik).
This could be after an update to kdelibs4 (or possibly kdeedu-data kdelibs kdelibs-bin kdelibs-data libkdeedu1 oooqs-kde). Removing the contents of /tmp and .kde has no effect.
Check to see if you have the kdelibs 3.1.4-3 files installed, if so thats probably your problem. I've been looking for a resolution on this for days, the only one I've found has been to install version 3.1.4-2 of all these kdelibs files, problem is I can't find version 3.1.4-2 anywherre.
If you can find them, please let me know so that I can fix my messed up KDE too!
David