There could be a number of problems. The certificate name/owner should match the exact website name used. It is possible the browser gets stuck with validation of the certificate although usually you get a warning indicating the certificate details do not match the server specified in the URL.
For more detailed information, I would check the Jetty website (http://jetty.mortbay.org) and the Jetty mailing list for more help on the certificate installation. However, I have found the standard instructions for certificate installation to operate successfully.