Board Thread:Help Desk/@comment-60.242.75.64-20130208125441/@comment-7489479-20130328134204

First reinstall it on Steam (Right Click on Terraria in the Library -> Delete Local Content) then go to Programms (x86) -> Steam -> SteamApps -> common -> Terraria there you delete everything whats inside. Now you reinstall it, the problem should be gone. If it's not delete your saves located under MyDocuments -> MyGames -> Terraria -> Players / Worlds if it's still not working post here.