You say youve turned off all mods but since the last patch, the only way to be sure is to goto your trainfever folder and delete the ‘res’ folder. Then in Steam, find Properties and then Varify Game Cache and it will redownload a fresh instal.
This was quoted by the developers in their recent update,
Because the modding system has been completely reworked, we highly recommend that all players who have installed mods should clean their game installation. To do so, please first delete the “C:\Program Files (x86)\Steam\SteamApps\common\Train Fever\res” folder and second run the “Verify” option in the Steam client (Steam Client -> Train Fever -> Properties -> Local Files -> Verify Integrity of Game Cache”).
