Well,
http://www.paduaprep.com/forum/ is currently throwing a scripting error and not a 404 (webserver) error; indicating that it is now attempting to load the ubb files, though i'm not sure why it's throwing the current error, quite possibly the paths in the config file aren't set appropriately.
As for any redirects, the UBB wouldn't know your site A from your site B to be able to throw a redirect like that; so there should be a config file error, or a redirector error if you'd added some sort of redirector files.
