to be sure to have the right java version, download it directly form your LMS server. It is located in the following directory:
NMSROOT/htdocs/plugin
(where NMSROOT is your installation directory (default on windows: C:\Program Files\CSCOpx; default on Solaris: /opt/CSCOpx)
the easiest way is to copy the highest available version in this directory to you client machine and then start the installation (there is a version for solaris clients and windows clients).
Close all browser windows on your client while installing to avoid a reboot;
If this does not work on your client, first uninstall all versions of Java from the client through 'Start - Settings- Control Panel - Add/Remove Software' and redo the installation of the JRE you downloaded from your LMS Server.
BTW - check if your browser has any pop-up blocker enabled and disable it