Can't log onto Second Life?

So I just downloaded second life the other day and I haven't been able to log in. Every time i log in it gets to 'waiting for region handshake' then it says 'unable to connect. login packet never received by login server.' Is this a problem with the server or with my computer. I went into the windows firewall and made sure the program was allowed, however my computer came pre-installed with anti-virus wear so i'm unsure if I need to change something else. I've searched my computer and virus wear and can't seem to find where else it could be blocked by me. Any info would be helpful thanks