I have upgraded from kde4.1.85 to 4.1.86 last night and now kdm fails.
There is no kde login screen, I have to login as root and startx, but
login as me with startx fails.
I have solved the problem, The auto login was set to a user that has a
problem with the kde4 configuration. Even after renaming the .kde4
directory it still could not auto login to the user and was dropping
back to a shell login.
disabling the auto login enabled the kdm login to function. The kdm
changed from startkde4 to startkde in /etc/sysconfig/windowmanager,
don’t know if this was necessary.
There needs to be better or easier to find documentation in kde
techbase.
The change to ‘akonadi’ in kmail seems to be the culprit in the latest
kde4.2beta2.