Here's the code that checks whether the user is in NAB (see my comment):
http://www.experts-exchange.com/Q_23659176.html#a22259860Bellow is Andrew Polak's code that gets all users in a group, but you don't need recursion if you just want to check whether there are "hanging users" in groups. Simply use his code as the guide to write your own agent that would use ($VIMGroups) view to get each group document and check whether each of the users is in the NAB using the function from the link I posted.
Notice this line:
Forall member In doc.members ' for each entry in the the group
FYI, if you want to disallow someone access you should create Deny Access Group in NAB and add him there. He wont be able to access the server no matter which group he's in...
