So I recommend, reupload all the original vB non-image files (except install.php). Make sure you upload these in ASCII format and overwrite the ones on the server.
Next disable all plugins. Edit your config.php and add this code right under <?php
Code:
define('DISABLE_HOOKS', true);
If you don't get the problem after turning them all off, then turn them on one-by-one until you do get the problem.