Version: (using KDE 4.2.0) Installed from: Fedora RPMs I tried to change the locale on Regional Settings. After adding a Language and the hitting apply the applying settings dialog box shows up and then the progress bar indicates that it is working and then it starts over and over and over and over. It then gets slower and slower and slower. Finally, I had to restart my computer. My kde profile was cprrupted. Nothing would show up in my system tray. Good thing I had a recent backup of it or I would have had to start over.
I just tried this again. I don't know if makes a difference but, this time I did it from Korganizer's "Configure Date & Time" menu item and things seemed to work OK.
Since it works for me, apparently worked for you and didn't get any confimation in over a year, I'll mark this as worksforme :)