and today I found the fix:
"There are two ways to turn on color profile support in Firefox 3. The easiest is to install the Color Management add-on (which will work with Firefox 3 Beta 5). After you install the add-on and restart Firefox 3, color profile support is enabled."
taken from: http://www.dria.org/wordpress/archives/2008/04/29/633/
That's it. So very simple.