script version upgrade, and htaccess problem

My script authors had upgraded, the script version. i am i need to code, my mods into the new version. my previous pages([login to view URL], [login to view URL], and [login to view URL]) these can be view at [login to view URL] the new script version is similiar to the old.. this can be viewed at [login to view URL] old users info will need to be SQL into my new databse format(may need some adjusting) having a httacess problems: i receive the 404 error, when got to a users url, such as [login to view URL] this i would like rectified. please bid if you have experience, and a review. thanks