Here is another work around that doesn't require a compile with Visual Studio.  You can just edit this one file.  Look at \DesktopModules\Admin\Authentication\Login.ascx.vb and look at line 657 in the Page Load Event Handler.  Add a ' (apostrophe) before lines 657 and line 670.  This will comment out the logic that does the check for the Login Module.

 NOTE: You will have to watch out if your ever upgrade the site later!!!

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

' Verify if portal has a customized login page
If Not Null.IsNull(PortalSettings.LoginTabId) And IsAdminControl() Then 
      'If ValidateLoginTabID(PortalSettings.LoginTabId) Then  <-- Comment out this line
            ' login page exists and trying to access this control directly with url param -> not allowed
            Dim params(2) As String
            If Not String.IsNullOrEmpty(Request.QueryString("returnUrl")) Then
                  params(0) = "returnUrl=" & Request.QueryString("returnUrl")
            End If
            If Not String.IsNullOrEmpty(Request.QueryString("username")) Then
                  params(1) = "username=" & Request.QueryString("username")
            End If
            If Not String.IsNullOrEmpty(Request.QueryString("verificationcode")) Then
                  params(2) = "verificationcode=" & Request.QueryString("verificationcode")
            End If
            Response.Redirect(NavigateURL(PortalSettings.LoginTabId, "", params))
      'End If <-- Comment out this line
End If  

RRRRGH...

This is actually a bug... thanks to your posts, I was able to deal with the issue without "touching" the base code. I went into the database and edited both the Modules table and the Desktop Modules table to give my custom login module the friendly name "Account Login".

No more errors from there on...