Shared Function _    LogonUser(ByVal userName As String, ByVal domain As String, _    ByVal password As String, ByVal dwLogonType As Integer, _    ByVal dwLogonProvider As Integer, ByRef phToken As Integer) As IntegerEnd Function Shared Function _    CloseHandle(ByVal hObject As Integer) As IntegerEnd Function' Check whether a username/password pair is correct'' if DOMAIN is omitted, it uses the local account database ' and then asks trusted domains to search their account databases' until it finds the account or the search is exhausted' use DOMAIN="." to search only the local account database'' IMPORTANT: works only under Windows NT and 2000Function CheckWindowsUser(ByVal userName As String, ByVal password As String, _    Optional ByVal domain As String = "") As Boolean    Const LOGON32_PROVIDER_DEFAULT = 0&    Const LOGON32_LOGON_NETWORK = 3&    Dim hToken, ret As Integer    ' provide a default for the Domain name    'If domain.Length = 0 Then domain = Nothing    ' check the username/password pair using LOGON32_LOGON_NETWORK delivers the     ' best performance    ret = LogonUser(userName, domain, password, LOGON32_LOGON_NETWORK, _        LOGON32_PROVIDER_DEFAULT, hToken)    ' a non-zero value means success    If ret Then        CheckWindowsUser = True        CloseHandle(hToken)    End IfEnd Function