Sometimes the redirect function from Page Lists Plus fails. This happens when the target URL is too long (100+).
The plugin adds some collumns to posts table in the database.
The redirect_url is set to type varchar max length 100. If you increase this value, or change to type text, everything will be fine.
Is it really necessary to close unresolved threads to new replies? I had to make up a new thread for this but there were at least two unresolved closed ones. Just an idea :)