Unfortunately bookmarked links no longer work when topics move into the archives.It's not the best solution, but there is a somewhat easy workaround to the problem..
If you have a "live" topic URL like the below and it stops working, simply take the number listed before the ".shtml" at the end of the URL and use it to replace the "18" that you see listed after the "om=" part of the below sample archived topic URL.
Sample "live" topic URL:
http://community.realitytvworld.com/boards/DCForumID6/17816.shtml
Sample "archived" topic URL:
http://community.realitytvworld.com/boards/cgi-bin/dcboard.cgi?az=show_thread&om=18&forum=DCForumID6&archive=yes
These examples are both from the Off-Topic forum, so if you are dealing with another forum you'll also have to make sure the "DCForumID" number is also changed to reflect the DCForumID of whatever other forum you are dealing with.