When moving your vbDrupal installation you need to be careful to update all the configuration paths. You may need to do this if you change hosting companies or plans, or if you just want to update the directory structure of you site (maybe to change your forum location from www.example.com/forums to forums.example.com and your hosting company has explicit sub-domains directories).

1. First, use your favorite FTP or file manager program (or by using a shell account if you prefer) to move the folders to the new locations. Make sure that all file and directories still reside in your 'public' or 'html' directory and that the structure of Drupal and vBulletin are maintained. Also, you must not have both Drupal and vBulletin reside in the same directory since their index.php files will conflict with each other.
2. Then you need to update your server or hosting package to map your URLs to the new locations. Typically your base URL of www.example.com should point to the drupal folder, and forums.example.com or www.example.com/forums URLs point to the new vbulletin folder.
3. Next, update your config.php file in the vBulletin ‘includes’ directory to have the $config['Misc']['forumpath'] variable point to the new location (this must be the full system path, not a URL). If you have changed hosting companies, this path may have changed drastically.
4. Now, you need enter the admin control panel of vBulletin (if the page does not display, then your server configuration is not set correctly). Enter the vBulletin Options page in the Admin Control Panel and open the vbDrupal section of the Options. Update both the Drupal URL path (may not have changed) and definitely the Drupal system path to the new location by typing the new infomation in the appropriate text boxes.
5. Lastly, update the Drupal settings.php file located in the ‘sites/default’ directory. Find the $vb_dir variable and update this path to the new location. Repeat this step for each site if you have a multi-site configuration.
6. Now open your browser and navigate to your Drupal installation (www.example.com). If you have been careful and entered everything correctly, the Drupal portion of your site should open. If not, try running the Drupal update.php script. It should automatically update your Drupal paths in vBulletin. It will also tell you if it can't find the vBulletin installation.

You should now have your vbDrupal system back up and running.