Comvigo IM Lock 2006 uses a simple substitution cipher to encrypt a password stored in the msnvs\prc registry value, for which all users have Read permission, which allows local users to bypass the product's blocking functionality by decrypting the password.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25219
http://www.vupen.com/english/advisories/2006/0866
http://www.securityfocus.com/bid/16988
http://www.securityfocus.com/archive/1/426935/100/0/threaded