We have just published KB article 2533860 "Error TF215106 or TF225000 when trying to Delete or Create a New Build Definition In Team Foundation Server 2010 Team Build" on updating the Build permissions for upgraded servers. If your TFS server is upgraded from a previous release to the 2010 RTM or SP1, you should run the provided code in the KB article to correct the Build permissions for the Project Administrators group of all existing team projects.