PGP Desktop before 9.10 allows local users to (1) cause a denial of service (crash) via a crafted IOCTL request to pgpdisk.sys, and (2) cause a denial of service (crash) and execute arbitrary code via a crafted IRP in an IOCTL request to pgpwded.sys.
https://pgp.custhelp.com/cgi-bin/pgp.cfg/php/enduser/std_adp.php?p_faqid=1014&p_topview=1
http://www.securitytracker.com/id?1022034
http://www.securityfocus.com/archive/1/502633/100/0/threaded