ver 1.71

I got automatically updated to version 1.71 and i'm playing a game in 1.66. Does this make a difference.

I'll answer my own question- it must do as i get the error "the data files currently being used do not match the data files that were used when this game was started."

Surely I must be able to play an older version game when i get a newer version? (I had no choice on the install steam did it for me!