Javascript error : Drupal.settings.viewsSlideshowSingleFrame is undefined

I've a strange error with views slideshow with single frame :
- When i clear cache, everything is working fine
- If i reload the page, i have a Javascript error (Test on firefox and IE8) :
Erreur : Drupal.settings.viewsSlideshowSingleFrame is undefined
Fichier Source : /sites/default/files/js/js_8f4f87cb705afe28f98d3a00b6fb6295.js
Ligne : 932
Thanx in advance