Makes sure authors and editors cannot submit advanced metadata on a post when the advanced tab in the metabox has been disabled for them. Thanks Peter Allor from IBM for finding and reporting this issue.
Fixes a bug where upgrading to version 2.3 would occasionally cause WSOD's on both admin and frontend. We were unable to pinpoint the exact conflicting plugins and themes, but we are quite confident it was caused by us using, and others hooking into, WP_Query too early.