I'm using KDE for a desktop in my own account and Gnome in my root account. I'm on a single standalone box with nothing but a dialup ISP. I've been using kppp for adialer in both accounts, successfully until 6.1. I ran into the problem with kppp asking for the root password when brining it up in my user account, and wound up reloading 6.0, then 6.1 without the kdenetwork package. Worked fine. I then loaded the StarOffice that came with 6.1. I tried both the network install and the single user install from my user account. After running StarOffice I'd try to log on and got a message saying that the kernel did not support ppp. I logged in as root and ran kppp and it worked just fine. Then logged back in as myself and kppp would work fine until I ran StarOffice. I finally uninstalled StarOffice and it destroyed my KDE settings in my user account. Staring over.
If the problem was caused by kppp, it's probably fixed with the new KDE RPMs (they fix a number of bugs). If it was caused by Star Office, there's no way we can fix it - unless you can convince them to release source.