Error while initializing sound device for the root account
Symptom:
During load, KDE reports the following error messages when launching X as a root user. The sound works previously.
Error while initializing the sound driver. device: default can't be opened for playback (Invalid argument). The sound server will continue, using the null output device.
Cause:
When exiting KDE as a regular user, the system removes some audio configuration files.These configuration files are created on the fly for regular user, but not for the root account. Once these configuration files are deleted, the root account can no longer access the audio device
Solution:
Before starting KDE as a root user, run 'ainit root start'. That will create the missing audio configuration files.