Invalid certificate authority signature
The certificate chain presented by login.live.com does not have a valid digital signature from the Certificate Authority from which it claims to have a signature.
This is with pidgin-2.5.2 (the latest version in YDL 6.1 updates).
Ah, just checked the site: http://www.pidgin.im/
(2.5.3 is the latest source release available)We are aware of the problems connecting to MSN with Pidgin 2.5.3 and older. We hope to have a new release and packages out soon to fix this.