When you administer the Block all stations task or the Limit web access on all stations task for Windows MultiPoint Server (WMS) 2011 stations and then close the MultiPoint Manager, a new user session on a station is not blocked or limited to specified websites.
To resolve this problem, install the update rollup that is described in the following Microsoft Knowledge Base article:
2555129 Update Rollup 1 for Windows MultiPoint Server 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about how to block or unblock stations, visit the following Microsoft TechNet website: