Lync address book issue for only some users across the org

hi there,

we have around 10K Lync users in our infra, out of which only 5 users are having  address book issue.
It appears the below error message and search never happens in Lync address book. 

1. only 5 users are affected with the above error and the issue is unresolved even after I tried whatever the steps that are explained in the articles. 

http://blog.insidelync.com/2012/02/lync-address-book-client-synchronization-errors-and-common-problems/

http://blog.schertz.name/2010/09/updating-the-lync-2010-address-book/

2. its not desktop related issue, because from these computers, addressbook is working fine for other SIP IDs.

3. I tried in multiple computers but for this 5 users address book download is never hapenning in any computers, so I strongly beleive this issue is to be fixed from server side. 

4. I moved these 5 users to different pool, but no luck.

anyone please advise if you have any approch or resolutions to this issue.