The POP3 proxy service (POPROXY.EXE) in Norton AntiVirus 2001 allows local users to cause a denial of service (CPU consumption and crash) via a long username with multiple /localhost entries.
http://www.securityfocus.com/bid/5692
http://www.securityfocus.com/archive/1/291358
http://www.iss.net/security_center/static/10085.php
http://archives.neohapsis.com/archives/bugtraq/2002-09/0240.html