Tim,
This may be attributed to the actual source of the LDAP tree you have registered in the DLP console.
Try to start at the top fo the tree rather than going deepe. Also there might be an error, with on of the people in your AD groups. Take a look at the names you have in the DLP console. I have seen it where there is a bad user that is in the group that needs to be removed.
Can you create a new group based off the existing LDAP profile?
If this solves your questions please marked as solved.
Ronak