this reply is a bit late, but I found the question when I searched for something similar. If you still need an answer, you can try the following:
According to the MSDN library, the error is network specific. You can call WNetGetLastError to get additional information about the specific error.

Public Declare Function WNetGetLastError Lib "mpr.dll" Alias "WNetGetLastErrorA" (lpError As Long, ByVal lpErrorBuf As String, ByVal nErrorBufSize As Long, ByVal lpNameBuf As String, ByVal nNameBufSize As Long) As Long