Game Error: SteamGetEncryptedUserIDTicket Failed

http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=202

Like many of these blob file errors, the solution is to exit from Steam and delete a file in your Steam directory called:

ClientRegistry.blob

This would be either:

c:\Valve\Steam\ClientRegistry.blob

or

c:\program files\Steam\ClientRegistry.blob

(or wherever you installed Steam to).

The next time you start Steam it will re-create this file, do a brief update and then you should be able to connect and play.