When attempting to authenticate to KDE desktop, user is returned to login screen

While attempting to authenticate the system will appear to start the KDE desktop, but the user will be returned to the login screen.

 

Aside from deleting the user and the user's associated home directory (which usually resolves the problem) here are some things to look at that may help determine or resolve the problem:

1. Ensure it is not an authentication problem by booting to the terminal first, authenticating as the user in question. This will give a more direct look at any errors returned.
2. Look at the ~/.xsession-errors file for the user. An error related to the issue may be logged here.
3. Try removing the following files:

• ~/.DCOPserver_* and the /tmp/.ICE_unix directory (KDE's destop communications protocol which directs communication between KDE applications)
• ~/.kde/cache-hostname, ~/.kde/tmp-hostname, and /tmp/tmp-hostname (sometimes a corrupt cache will cause a failure. This will clear out the cache for that user.

4. Check to ensure that the /ect/skel/ directory has not been modified (ie this is where the initial .kde files for each user come from when KDE is started for the first time).
5. Check the file permissions against a working user in the users ~/.kde/ directory
6. If this is happening when users are first being created and trying to access KDE ensure that the $TEMPDIR variable is not set (ie it is defaulting to tmp). It appears that some parts of KDE may not use this variable and will still attempt to use the /tmp directory. This may not be an issue in cases where the variable is set and the /tmp directory still exists.