open_base_dir is a PHP configuration directive which limits PHP scripts to only reading/writing files in a specified directory (and its subdirectories). Some of the configuration directives can be used in an .htaccess file, but according to the PHP manual, open_base_dir is one of those that can only be set in php.ini.
I can't tell enough about your configuration from what you've posted.
I would first confirm what they've said by creating a script, e.g., phpinfo.php, consisting of the single line
code:
<?php phpinfo(); ?>
and running that script from a browser. After you've saved the output, delete that script. Then compare the value of open_base_dir with what they told you. Keep the phpinfo.php output handy, since it may contain other info that will be helpful in resolving this.
I don't know that they mean by
read_dump.php. I didn't see that file in the UBB.threads directory.
Sorry if you already know this stuff.
I'll take a look and see if there's a way of telling threads which tmp directory to use.
