The messenger server has a replica of the partition holding the users.
It's an OES 2 sp2 server, and the GW Messenger is 2.04.

Sometimes we see an error that says 'Library error' when adding a contact, or it doesn't show all users that exists with the search parameter given.
We also sporadically see a 'Library error' when some users log in to it.
Looking in the log I see an error that says 0xAE16 when users log in fails.

I can find the 0xAE11 error in the TID's but not the 0xAE16, I did find an article on the forums, mentioning this problem, they mention memory problems, so it seems to me there is a bug that needs fixing.