Most of new skins you can reinstall from the Image Server,
not as the default skin but as an extra skin.
It does not change a thing.
But you can copy default skin,
from /usr/share/enigma2/skin_default <all Folder and sub folders
and you have to copy skin.xml and prev.png files from /usr/share/enigma2/
The problem arises as said colleague
@Eragon
with updates and changes in the image coding.
In this case, it can happen to bring down/crash image.