I am not familiar with the linux environment, but were this a windows install of dominions, I would rename the folder and reinstall followed by the most recent patch. Maybe that would get you back on track?
Really wild-*** guess... Unicode/UTF. Special character 65533.
Any regional settings change recently? Problem with any directory name? Reset your internet connection.
also, check the ownership of all the files.
I can't guarantee these are nothing more than wild geese chases. Don't worry if these ramblings don't make much sense, but they should be relatively safe and easy things to check.