Dim m_Conn1 As ADODB.Connection

Public Property Get Conn1() As ADODB.Connection
   Set Conn1 = m_Conn1
End Property

Public Sub Main()
   Set m_Conn1 = New ADODB.Connection
   m_Conn1.CursorLocation = adUseClient
   If frmLogin.EnterTheApp Then
      frmMain.Show 'Это главная форма (MDI)
   End If
End Sub

Dim OK_Exit As Boolean

Public Function EnterTheApp() As Boolean
   
   Me.Show vbModal
   
   EnterTheApp = OK_Exit
   Unload Me
End Function

Private Sub btnOK_Click()
   If TryToConnect(txtUserName.Text, txtPassword.Text) Then
      OK_Exit = True
      Me.Hide
   Else
      MsgBox "Íåïðàâèëüíîå èìÿ ïîëüçîâàòåëÿ èëè ïàðîëü"
   End If
End Sub