Lync 2010 user getting locked out

Many posts about this on the internet but having been through this today with a customer think I have it cracked.

1. Exit Lync on users desktop
2. Unlock user in AD
3. Remove user certificate in Lync Control Panel
4. Remove local machine Lync user certificate
5. Remove cached credentials from users PC
6. Delete contents of C:\Users\%username%\AppData\Local\Microsoft\Communicator
7. Delete reg key HKEY_CURRENT_USER\Software\Microsoft\Communicator
8. Load Lync

If Lync prompts for a username and password then you still have the problem and at this point dissolve in tears.