To clarify, I was fighting with the same issue, and the cert needed to be reloaded in the cacerts within the jdk that ships with WebSphere. Reloading the one in /opt/WebSphere/AppServer/etc/DummyServerTrustFile.jks had no effect on the expired certificate problem.
here is where to get the new root certs for verisign and thawte.
Also, for more info on reloading certs, see this ]
article [ August 11, 2004: Message edited by: Steve Ferguson
[ August 11, 2004: Message edited by: Steve Ferguson ]