Empecé a recibir este error recientemente cuando intentaba iniciar sesión usando twitter. ¿Alguna idea de por qué?

Stack Trace: 


[AuthenticationException: The remote certificate is invalid according to the validation procedure.]
   System.Net.TlsStream.EndWrite(IAsyncResult asyncResult) +230
   System.Net.PooledStream.EndWrite(IAsyncResult asyncResult) +13
   System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar) +123

[WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.]
   System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult) +6432446
   System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar) +64