Try starting up the KDE Control Center from the command line so you can actually get some verbose output to post back to us.
If you know what a console/terminal/xterm/kterm is, open it. If not:
click on the "K" menu and locate something that looks like an old monochrome monitor (a black screen monitor). Basically, do what you can to get a terminal window open in your desktop environment (KDE).
This should start the KDE Control Center.
From there go about your business, try clicking whatever you want, and the window that opened the control center should give some feedback on what's going on behind the scenes.
We want that info.
Highlight it, and paste it in here so we can see if there are any obvious problems.