I see that you got it working, but for future users looking for a fix I'm going to type out what I was planning to.
This issue is due to a server setting that an overzealous security admin of your server needs to change; there is a setting for PHP that affects file_get_contents called "allow_url_fopen" which is currently disabled on your server (currently it's set to "0").
This setting affects the ability for PHP to fetch content that is located off of your server and display it asif it was a part of your site (in the case of UBB.threads it is a pretty big thing that affects everything from phpmailer, shareaholic, stop forum spam, etc; in the case of my UBB.threads Test script it communicates with the server to check for the latest build). As this is a security setting they likely don't have an override rule that'll allow you to change it yourself through a customized php.ini file.
