If the buttons aren't appearing, custom vBulletin's Custom BB-Code Manager. Do the wiki BB-Codes there have button images set?
If you are getting the message "The changes cannot be saved because another user has modified the article you are editing", then either your edit was saved and your browser submitted it again for some reason, or your site is not sending the time you opened the editor with the request.
If you have any other plugins/products that modify the editor, try disabling them and see if it helps.