Errors with xfce4-panel

I got an error that the xfce4-panel / Taskbar disappeared.
I solved it by right-clicking on the Desktop, choosing Applications, Settings, Panel.
After that it told me that it got no panel running, and if it should start one.
I answered yes and the panel would appear again.

After an reboot, I always got the question wheter it should start an panel.
As that was quite annoying, I looked for another solution to the problem.
I found the answer here: http://forum.ubuntuusers.de/topic/probleme-mit-panel-und-kiosk-modus/
Just delete the xfce settings like that:

rm -rf ~/.cache  
rm -rf ~/.config

After that, click the log out button, UNCHECK the “Save session for future logins” box and choose reboot.

On the next reboot, it should come up correctly again.