If you get the error message in Mozilla Firefox 4.0 Firebug
Image corrupt or truncated: <unknown>
Check to see if your site has the “favicon” setup correctly. Firefox 4.0 has a strict rule that requires your site to have the favicon.
You can set the path of the fav icon with the following HTML:
<link href="http://[YOURWEBSITE]/favicon.ico" rel="shortcut icon" type="image/x-icon" />
Dynamic Drive’s free tool for creating favicons:
http://tools.dynamicdrive.com/favicon/
