Steam won't even start..

[Dog--]

So I wanted to play it today, I ran it in offline mode, but it didn't let me play my games, it said they can't be played in offline mode, this has happened lots of times before, an update is usually needed for steam when this happens, so I connect to the net, let steam update, it updates to about 40%, then I get this error message:
http://img367.imageshack.us/img367/8413/18061584zr0.jpg

Now that is all I get when I run steam, I can't play my games... I am connected to the net, and it still says that, what do I do?

[PimpinPenguin]

Have you checked your firewall and anti-viruses, some Steam updates cause them to block steam.

[Dog--]

I was running another game (lined down) while I was trying this, as soon as I exited that game, everything works.. The game didn't even use the internet, that's sort of odd..

Thanks for the help, regardless.

[DEATHMASTER]

its happened to me before. Fixed by deleting the process steam.exe.