My computer, his name is Swan, I can connect to every computer in my local network, others can ping Swan successfully, however, some time, people want to access my computer, using the command below: \\Swan or \\192.168.20.121, In most time, they got an error below: You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions. The trust relationship between this workstation and the primary domain failed. However, in a few time, they can access my computer successfully, whats wrong with my computer? The configuration in my computer: Vista x86, Turned off all firewall, Turned off UAC. No any anti-virus software. Guest account is turned on I can ping domain server and router successfully, I can access Internet. In few time, people can access me. Error log in my event view: An account failed to log on. Subject: Security ID: NULL SID Account Name: - Account Domain: - Logon ID: 0x0 Logon Type: 3 Account For Which Logon Failed: Security ID: NULL SID Account Name: billchen Account Domain: ssw2000 Failure Information: Failure Reason: An Error occured during Logon. Status: 0xc000018d Sub Status: 0x0 Process Information: Caller Process ID: 0x0 Caller Process Name: - Network Information: Workstation Name: WIN-MDPCT19T7VJ Source Network Address: 192.168.20.201 Source Port: 21373 Detailed Authentication Information: Logon Process: NtLmSsp Authentication Package: NTLM Transited Services: - Package Name (NTLM only): - Key Length: 0 This event is generated when a logon request fails. It is generated on the computer where access was attempted. The Subject fields indicate the account on the local system which requested the logon. This is most commonly a service such as the Server service, or a local process such as Winlogon.exe or Services.exe. The Logon Type field indicates the kind of logon that was requested. The most common types are 2 (interactive) and 3 (network). The Process Information fields indicate which account and process on the system requested the logon. The Network Information fields indicate where a remote logon request originated. Workstation name is not always available and may be left blank in some cases. The authentication information fields provide detailed information about this specific logon request. - Transited services indicate which intermediate services have participated in this logon request. - Package name indicates which sub-protocol was used among the NTLM protocols. - Key length indicates the length of the generated session key. This will be 0 if no session key was requested.

Based on the error message, this issue can be caused by trust relationship. I suggest you first check the solution in the following threads: Vista Error "Trust relationship between this workstation & primary domain failed" http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=539503&SiteID=17 "The trust relationship between this workstation and the primary domain failed" error http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=3169456&SiteID=17 Trust Relationship Between Workstation and Domain Fails http://support.microsoft.com/kb/162797

Thanks a million, Sean, you help me a lot. I solved the problem by quitting my current domain and re-joinning it, after I restarted my computer, all are OK. A document in Microsoft website describes the cause: The computer's machine account has the incorrect role or its password has become mismatched with that of the domain database.