That is from a modification (or non-vb4 code).
Disable all your plugins/products except the Blog and CMS. And when I say disable them ALL, I mean all the products on the Manage Products page (except the Blog and CMS products)
AND all the plugins in the Plugin Manager (except those associated with the Blog and CMS). You must do BOTH (I can't emphasize that enough). Now see if you still have the same problem.
If you continue to have problems, please post over on vb.com for help. See this sticky -
Installation Issues / Questions or bug reports regarding default vBulletin 4.0