Use this forum if you have a relatively general question or comment about a game, Ventrilo, TeamSpeak, or Murmur/Mumble server with us. If you have a server-specific question that might not help out the community, please directly contact us through your control panel instead.
We have been seeing this alot lately. Usually that means its a VALVe problem and they will address it in the next update.
Untill then, you should be able to fix it be either restarting your server or restarting your client.