We currently have a SonicWall firewall, which does a pretty good job a blocking Social networking websites like Facebook and Bebo. The problem we are having is that sometimes we need to temporarily disable our firewall blocklist so we can update our company's page on Facebook for example. Whenever we do this, have see an avalanche of users logging on to their Facebook pages during work time. So what we need a way to block access while the firewall is down.

For the sake of argument, we have two groups of users - "management" and "standard users". "standard users" would have no access to Facebook, but "management" users would have access. Perhaps something like a host file redirect for non-management users. This could probably be enforced via group policy that would call a bat file to copy down the host file, depending if the user was management or not. I'm keen to hear any suggestions for what the best practice would be for this in a Windows/AD environment.

Yes, I know what we're doing here is trying to solve a HR problem using IT. But this is the way management wants it and we have a lot of semi-autonomous branch offices that we don't have a lot of day to day contact with, so an automated way of enforcing this would be the most preferable method.