The IRC component of Trillian 0.73 and 0.74 allows remote malicious IRC servers to cause a denial of service (crash) via a PART message with (1) a missing channel or (2) a channel that the Trillian user is not in.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2002-1471
http://www.securityfocus.com/bid/5776
http://www.iss.net/security_center/static/10162.php
http://archives.neohapsis.com/archives/bugtraq/2002-09/0268.html