diff -up lightdm-gtk-greeter-1.8.5/src/lightdm-gtk-greeter.c.bg_crash lightdm-gtk-greeter-1.8.5/src/lightdm-gtk-greeter.c
--- lightdm-gtk-greeter-1.8.5/src/lightdm-gtk-greeter.c.bg_crash	2014-05-05 13:39:10.833190035 -0500
+++ lightdm-gtk-greeter-1.8.5/src/lightdm-gtk-greeter.c	2014-05-05 13:41:53.725481558 -0500
@@ -2060,7 +2060,7 @@ set_background (GdkPixbuf *new_bg)
         {
             gdk_screen_get_monitor_geometry (screen, monitor, &monitor_geometry);
 
-            if (bg)
+            if (bg && (monitor_geometry.width > 0) && (monitor_geometry.height > 0))
             {
                 p_width = gdk_pixbuf_get_width (bg);
                 p_height = gdk_pixbuf_get_height (bg);