Hoooolala:
1) the newthread.php file is one that you already had. You need to edit your current newthread.php file and then re-upload the new edited one.
2) Strange, i am also getting the EXACT same problem. Your problem is probably occuring because you did not update the newthread.php file. Make sure you download this file, edit it, and then re-upload it. Hopefully this works out for you.....Mine is still not working