Uninstall NSS via normal removal procedures. (Add/Remove programs )
Please Note: During the uninstall of NSS, you should select the top option "I plan to reinstall a Norton Product in the future. Please leave my settings behind." The reason for the backup (Export/Import of ID Safe data) is a safety factor.
Once installation is complete, open NSS and manually Run LiveUpdate (located on drop-down under PC Security on left side of main page of NSS) as many times as necessary for it to respond "no more updates available". If a reboot is requested, reboot and then continue to Run LiveUpdate until it responds "no more updates available" and then reboot one last time. Your installation should now be up to date definition wise and ready for use.