This topic was reported by PC Magazine. I didn’t read all the detail but the only first paragraph, and that’s enough for me to hold off on updating to Leopard 10.5.6. (only the topic is enough actually) I’ll wait and see how Apple handles this problem. v10.5.7 could be soon to come.

I’ve just automatically update Firefox to v3.0.5 this morning, and now i’m praying not to have any serious bugs in this update. I shouldn’t set automatic update on anything without asking.

http://www.pcmag.com/article2/0,2817,2337045,00.asp