This is for those unlucky folks who found KDE 4.0.2 frequently crashing and want to go back to 4.0.1 now.
It took me some time to figure a way out. The challenging part was to recover the KDE 4.0.1 packages, which ppa launchpad no longer hosts. I posted this query regarding this on the kubuntu forum, and a user was kind enough to upload the packages online.
Here are the steps to get back to 4.0.1..
1. First remove all KDE 4.0.2 packages using synaptic. Also remove ppa launchpad from the synaptic > settings > Repositories > Third-Party software.
2.Now Check your /var/cache/apt/archives if you still have the KDE 4.0.1 packages from your previous install/update.
3. If you do, then copy them to a separate folder. These are files that you need.
4. If you don't then download these i386 packages for KDE 4.0.1 (211 MB) and extract them to the debs folder.
5. Now, you need to build local APT packages. Change to the debs folder and run
$ cd /home/anoj/debs
$ sudo dpkg-scanpackages . /dev/null | gzip -9c > Packages.gz
6. Now let's start using these packages. Edit your sources.list file and add the path of the package
$ gedit /etc/apt/sources.list
Add these lines at the end of the file
deb file:/home/anoj/debs/ /
7. Update the apt package index
$ apt-get update
8. Fire up Synaptic. Search for kde-4. Now start installing the KDE 4.0.1.
My Kubuntu forum post
How to build local APT Repositories