Those broken links are available on another website outside Nabble. Someone created a page (in the amazonaws domain) and added broken links to your site. So the problem is not in your forum, but on a page that we don't control. Google has been crawling that page and listing the broken URLs for you. You should try to contact the owner of that page and see if he/she can fix the problem.
"This topic was created a long time ago and a new reply here would be confusing to a lot of people.
If you have questions about this subject, please create a new topic and link to this thread if needed."
You see this message because you have enabled the "Lock old threads" module. Click on Options > Application > Extras & add-ons and uncheck the Mailing List Archives / Lock old threads module.