Check your Steam Internet Connection Speed setting:

[silentsentinel]

Some people have had odd problems lately, try checking the Internet connection speed setting under File > Settings > Internet in the main Steam window. My settings somehow got reset, so maybe yours have too.

[Relly]

My settings stood the same.. but I'm having a hard time staying connected to a server. My game freezes, crashes.. and the only way I can restart is by pushing the button on my case... can't even ctrl alt del

Alot of people are experiencing the same thing as well. I haven't slept trying to fix this.