Hey,
That can happen when your steam client is out of date. IE you launch the game with applaunch or you just start the game before it can check for updates, or while it is. More specifically if steam.dll is out of date this will be the "error" that is thrown. No worries, as was said just relaunch itll finish updating and your good to go
Josh Tacey
Technical Manager
CyGamZ: Ann Arbor
National Amusements, Inc.
REMOVE-jtacey@national-amusements.com