Failed to validate certificate with 7u21 for "abljem"

Java version: 7u21

OS: Windows XP

Browser: IE, Chrome and Firefox

Applet Name: abljem

Bug description: A user reported the following: "I got this message when I try to run the application on 2 computers, with Windows XP and Windows 7.
I tried using Google,Internet Explorer and Firefox. They all show the same warning here below:

Warning-Security
Failed to validate certificate.
The application will not be executed.
Name: abljem"

Reproduced by Java.com team: No, was not able to reproduce.