All stats wiped. Additionally, I keep getting "unable to unlock achievement, please check storage device" (left over 360 code, cute) errors, and it will not retain new stats either. Had to exit Steam entirely and re-enter for stats to reset to normal.
Check your other Steam games. If this happened, it's likely something happening to the Steam Cloud. [PS:] Were you on Aussie servers last night? I was playing someone there, and they said this happened to them.
