The only other thing I can suggest is to uncheck the 'USe Session Security' box and try again (If you haven't)
You could also try to re-download the theme files from our github and upload them to your server replacing the existing ones. (In case a file has gotten corrupted)
You could also try to re-download the theme files from our github and upload them to your server replacing the existing ones. (In case a file has gotten corrupted)