Garry's Mod won't start up

[Tta25]

I got Garry's Mod a few days ago and I got the new update that came out on the sixth I believe.

Long story short: I got update, and now I can't even play it. It goes to the loading screen, cuts to black and sends me back to the desktop.

Can anyone help me with my problem?

[highlight](User was banned for this post ("wrong section" - postal))[/highlight]

[c👌de_g🎷]

[url]http://facepunch.com/showthread.php?t=1286502[/url]
[url]http://facepunch.com/showthread.php?t=1286476[/url]
[url]http://facepunch.com/showthread.php?t=1286698[/url]

Reference threads; people have been having this problem a lot for the past week.

[editline]8th July 2013[/editline]

Where is your Garry's Mod folder located? /steamapps/(username) or /steamapps/common?

[Tta25]

/steamapps/common

Thanks for the reference threads by the way.