Recently whenever I try to join a server, It loads up. The moment it finishes downloading map, it closes and goes back to my screen. no errors.
my antivirus history show me entering fullscreen mode and exiting that mode moments later.

Possible solutions?

Take off the firewall that might help

i have exactly the same problem now, but it is not my firewall/anitivirus, got anymore suggestions to fix this?

Strangely, just happened to me, and was about to post a topic about it -.-

This just happened to me too :/

Most likely a server kicking you for high ping.

Mate, it's every server. I've never been denied access, so i'm highly doubting a ping kick, aswell, the screen freezes at 100%, as esc won't work until it crashes and shuts itself, So it isn't a ping kick.

Crap computer?

The same thing has been happening to me just recently. Certain I haven't changed anything in my installation and was playing fine just a few hours ago.

is this getting answered, or just ignored?

It just happened to me too. I was just playing and when I left to join a different server this happened.

Don't press "Esc" It's what happened to me over twenty times.

Yeah, this is happening to me right now, all four servers with any significant population, I get the loading bar to 95-100%, and then it drops back to desktop without me doing anything, and no message box.

Did a repair reinstall, no difference. Uninstalled and reinstalled, no difference.

(The obvious question is: what's changed? The answer, as far as I can see, is "nothing". Maybe my network provider is fucking with me? Comcast cable, Washington state. But getting info out of the game about why it's exiting would be nice.)

At me too. Autoclosing after downloading map, Windows 7 PRO.

Same here, starting to get annoyed with servers not opening.

Same problem here, I uninstalled it then reinstalled it didn't work I also cloesd my anti-virus (Kaspersky PURE) and my firewall

Autoclosing indeed. I have no idea what can cause that because I've played it just yesterday and everything was fine.
Reinstalling didn't work, BTW.

now its happening to me! someone help!!!!!!!

:( It is happening to me too.
I've tried reinstalling, restarting my computer, and everything.... I don't know why it won't work! D:

EDIT:
I just tried and tried and tried and now it is back up! :D

Logged in just to bumbthis post as its started happening to me too exactly as others have described it.

Exact same problem here.

Exact the same here to..

But how is it possible that like 21 people posted this problem, and still no one has a solution.. ^^

@Totem: How much did you trie before it went back up..? And what did you trie.? ;)

same thing happened to me i just reinstalled .49 and i works just fine:)

Indeed, Re-installs seem to work good.

Reinstalling didn't work for me.

But it did spontaneously fix itself overnight.