To troubleshoot this, please remove any hacks and disable your plugins, then see if you still have this problem.
Note: To temporarily disable the plugin system, edit config.php and add this line right under <?php
define('DISABLE_HOOKS', true);
If so, 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.
I did this and I still get the same error. I did try uninstalling a few products/plugins but that didn't solve it either.