XFCE crashes due to wrong icon theme selection
From Granular Linux Documentation
Problem
Sometimes when playing around in the fast & lightweight XFCE desktop it may happen that due to the wrong selection of icon-theme, XFCE won't start the next time. The wrong selection of the icon-theme could be probably because you accidently (or intentionally) selected the mouse cursor theme instead of the icon-theme.
Solution
You can correct this problem by following these easy steps:
- Log in normally into KDE.
- Open your Home folder and click on View > Show hidden files.
- Now navigate to .config/xfce4/mcs_settings.
- Open the file gtk.xml. Find & change the value of the variable IconThemeName to the original value, say Rodent.
- Logout of KDE and log into XFCE. Viola!!! Your problem has gone for good.

