If I recall correctly, I think other players with this issue were able to resolve it by simply removing (e.g. deleting) the entire contents of the game's "Cache" folder. I.e. from: "C:\Users\[Windows_User]\Documents\My Games\TerraTech\[Big_Number]\Cache"
They're just temporary files, so there's no harm there. Restart the game after doing it maybe.
Output log file in; "C:\Users\[Windows_User]\AppData\LocalLow\Payload\TerraTech" This is a hidden folder, so you may have to change Windows view options to see. Of course, be best to grab a log file before deleting cache.