Riet
Tomcat Pilot
This was where I was going next but then I forgot about this threadI've brought up old Hawking quote "Saying what came before the big bang is like saying what's north of the north pole" before. There are some pretty good objections to this idea - Though I do think it's a pretty good candidate for a semi-final answer.
A lot of the objections attack the idea of time just 'starting' for no apparent reason - We do have examples in quantum and even newtonian mechanics to support this sort of thing happening, but for a lot of people it just isn't enough.
Furthermore, the idea of 'infinity' seems to present some conundrums and there are some other ways to think of causation without time.
As a rambling explanation of the debates I've had with people on that topic - in this thread.
Edit: Whoo complex time.