I have this strange thing, the page validates well and the images load fine on IE.. only on firefox the image does not load, except when i save very high compression.. the image is now 65 kb.. when i get it half of that it does work?

Has anybody seen this behaviour before it is starting to drive me nuts :| unfortunatly i cant use the super high compression because then i get artifacts.

HTML Code:
#header {
    background-position:right top;