I have several AD groups titled in the following fashion: Domain Users INS1, Domain Users INS2, Domain Users INS3 and Domain Users.  My domain account is a member of Domain Users INS1 and Domain Users.  I have created these accounts in DotNetNuke.  I noticed that I was a member of Domain Users INS1 earlier this morning.  Then, without changing anything, it removed me from that group.  I've logged out and back in several times, then it eventually put me back into the group.  No changes were made in Active Directory or DNN, I just logged out and back in.  I'm using DNN 5, and the latest AD module.  I've checked my group membership on all domain controllers and it is consistent. This isn't the first time that this type of behavior was exhibited.  

I was wondering if someone can shed some light on what may cause these issues to arise, and if there is some sort of a log which I can use to troubleshoot.

Please excuse me, I'm new to these forums and assumed that I would automatically receive notifications.  I just found the "My Posts" link and saw that there was a reply.  I eventually did correct the error, and it was a problem with the domain.  The user account did not have permissions to query group membership on all accounts.  We changed this and the role synchronization worked.  I do have outstanding issues, but these are already being addressed in another forum, so this can be marked as resolved.