Why am I getting "Error: IO Error" when I add new .torrent downloads?
What does this mean? This error usually means the .torrent file itself is invalid, i.e. is not a properly encoded torrent.
How do I know? Check to make sure that torrent file really contains torrent data. You should see file-names and tracker URL(s) if you open the .torrent file in notepad or another editor. If not a complete, encoded torrent file, then Azureus cannot use it. Often you can see what's wrong by reading the .torrent text, which is really just html.
What do I do? You need to somehow download and give Azureus a complete, proper .torrent file.
If the website employs referrer checking, you'll need to click the download link directly, or use a downloader that can send a referrer id (NOTE: Azureus 2105 CVSB43 and newer allows setting of the referrer via File-Open-URL). NOTE: The "referrer" page URL is not necessarily the URL showing in the browser "address" box (you need to, for example, right-click on the bit of the page where the link actually is and get its properties). Sometimes it helps to try to download it with another browser. So if you have problems while using Firefox try the Internet Explorer or another one you have installed.
Sometimes the server is overloaded or badly configured, and returns truncated data or error messages, in which case you probably have to wait a while for the server to recover.
You can also check if that particular torrent is available from elsewhere.
Read the Azureus FAQ