Error loading GDM theme

All I remember is that I cocked something up the night before the removalists came. Now it's been 2 months in shipping, unboxed it and it says:

There was an error loading the theme GDM-SuSE

Can't open file /opt/gnome/share/gdm/themes/GDM-SuSE/GDM-SuSE.xml

PS: Solved by reinstalling gdm and anything else that complained after that.

Gonna move across to Ubuntu on my main machine. For one thing, I've grown very friendly with ubuntu on my laptop while my main PC was away. But then reinstalling Myth could be a 'mare.