I am running an Samba 3.4.* Server with LDAP Backend on Ubuntu 10.04 LTS as a PDC for purely Windows 7 Clients (about 50). It worked quite fine for a long time, but now sometimes on some machines (really strange to replicate) I cannot login, because he tells me that there are no logon servers. When I look in the machines eventlog after logging in locally, the only error it shows is: "RPC Server is unavailable". The system was ported quite a while back from another machine running the same software versions to this new one. Are there maybe trust or caching issues between the workstations and the domain controller? The number of machines affecting is steadily increasing and so do you know any reason as to why this problem occurs? Any information on workstation and domain trust would also be welcome (After googleing I did not find anything really enlightening).