GECKOFX VALIDAR CERTIFICADO

'Añadir evento al iniciar el formulario
  AddHandler CertOverrideService.GetService().ValidityOverride, AddressOf CertOverrideService_ValidityOverride

Sub CertOverrideService_ValidityOverride(sender As Object, e As Gecko.Events.CertOverrideEventArgs)
        e.OverrideResult = CertOverride.Mismatch Or CertOverride.Time Or CertOverride.Untrusted
        e.Temporary = True
        e.Handled = True
    End Sub

Private Sub GeckoWebBrowser1_NSSError(sender As Object, e As Events.GeckoNSSErrorEventArgs) Handles GeckoWebBrowser1.NSSError
        CertOverrideService.GetService().RememberRecentBadCert(e.Uri, e.SSLStatus)
        Dim refUrl As Uri = GeckoWebBrowser1.Url
        GeckoWebBrowser1.Navigate(e.Uri.AbsoluteUri, GeckoLoadFlags.FirstLoad, refUrl.AbsoluteUri, Nothing)
        e.Handled = True

    End Sub

https://bitbucket.org/geckofx/geckofx-33.0/issues/5/uses-an-invalid-security-certificate