Application's digital signature has an error

Prompt started coming up few days ago for our end users.

“Application’s digital signature has an error. Do you want to run the application?”
Name: com.Percussion.cx.PSContentExplorerApplet

“The digital signature was generated with a trusted certificate but has expired.”

They’re running IE7 with Java Plug-in 1.6.0_03
Using JRE version 1.6.0_03 Java HotSpot™ Client VM

Selecting “Always trust content…” check box, prevents it from coming up again.

No recent changed were made to this environment (Daylight Saving Time?), so wondering why now?

See the announcement: http://forum.percussion.com/showthread.php?t=2576