"System Locale Charset" error in KDE

As root type in.....

dpkg-reconfigure locales

.....and make sure only the "en_GB" option is enabled before pressing ok.

Type in.....

Locale

....as both root and user. You may further need to type in.....

export LC_ALL="en_GB.UTF-8"

Hit ctrl, alt, backspace to log out of KDE. Log back in again the problem should be solved.