Incase you have upgraded to a version of KDE and are having issues and want to roll back to an older version, here is a quick way to do it. This will assume you are using a line in your /etc/apt/sources.list similar to the following:
deb http://kubuntu.org/packages/kde-354/ dapper main
Here is what you need to prepare for the downgrade.
You'll need to edit, or create, a file called preferences in the /etc/apt/ directory. Do the following commands:
kdesu kate /etc/apt/preferences
Then add the following lines to that file and then save it:
Package: * Pin: origin kubuntu.org Pin-Priority: 1001
Then you need to change the sources.list line we showed you above to match the following:
deb http://kubuntu.org/packages/kde-353/ dapper main
Then perform the following commands:
sudo apt-get update && sudo apt-get dist-upgrade
If you get any errors on packages not installing, then perform the following command:
sudo apt-get install -f
This should finish the downgrade without any further problems. Once that is done, perform the following command:
sudo rm -f /etc/apt/preferences
You should now have KDE 3.5.3 installed once again if you followed the directions exactly as above since we used KDE 3.5.3 as an example.