Try to run the update or liveupdates for Symantec and see if that will
help. If LiveUpdate will not find necessary updates, you may want to try to
run the autofix tool online which requires Internet Explorer: http://www.symantec.com/home_homeoffice/support/selectproduct_ts.jsp
Since Symantec/Norton is an antivirus program, and not an antispyware
program, you should try a scan with, say, Ad-Aware. http://www.lavasoftusa.com
You may in the end have to uninstall and reinstall Symantec.