Running Iceweasel 3.5.15 works fine for me even after a clean debian install. Probably some idiosyncratic bug in your configuration. Either reinstalling iceweasel or debian as a whole should have fixed the issue (and I'm assuming it did because you haven't updated the status of this bug). I'm recommending this bug is marked either unreproducible and more information needed or closed for the fact that this hasn't been addressed or updated in 5 months.
