kppp is actually a soft link: /usr/bin/kppp -> consolehelper Consolehelper asks for root password and then executes /sbin/kppp with root privileges. The problem is that, with this security method, when you modify your kppp configuration, you're NOT modifying $HOME/.kde/share/config/kppprc but /root/.kde/share/config/kppprc and this file is overwritten by *any* user with his/her own configuration.
fixed for next release.