So we can confirm that is a SSL issue, right?. I was trying to find a bug or a reason why some SSL packets are dropped, but without success. Anyway I think that I found a way to avoid the situation. I'll test it the next week.
Ticket from Stas, with video of the behaviour:
http://samer.ourproject.org/++/loading.ogv
He basically cannot use Kune. FF 12 in Linux.