If your host moved your site or changed servers then it is very likely either file/directory permissions are not correct or the absolute paths have changed.
First, FTP to your server and check and make sure all the files and directories still have the correct permissions per the UBB installation instructions.
Next, talk with your host on what the absolute paths would be for your new location. Then download the UltBB.setup file and check to see if you settings need to be changed. If they do, make the changes there. Reupload the file after any changes, and make sure you are in ASCII-only mode when doing so.
