I have enforced the "removable media lockdown" gpo for student computers. We are running Symantec Endpoint Protection 11. The problem is the computer says it got the policy but I can still use flash drives etc. If i force a gpupdate then the policy works. Should'nt this policy work when a student logs in, without having to force an update?

From what I remember, that GPO setting is only applied to Floppy Disks, CD/DVD-ROM drives, and similar removable media. Windows sees USB flash cards more as 'hard disk devices' and that policy doesn't apply to USB drives. Take a look at this article for a custom solution: http://www.petri.co.il/disable_usb_disks_with_gpo.htm