the old format was whatever it was for pre 6.5.. i can't remember what it was.. but i believe showflat, showthreaded and postlist.php are in your root dir to handle those incoming 'old style' links..
soo -- you either restore you import map, so those external links from other sites don't die
or contact those site(s) and give them the new link..
basically, someone must have a link to your pre 6.5x (i believe) posts/topics.. and they are linking to what that post or topic was.. the import map takes those links, translates them to your new installation and shows the topic..
