You are require to open the port for team viewer.
Read the article
http://portforward.com/english/routers/firewalling/Norton/NortonInternetSecurity2007/Teamviewer.htm
Norton thread
http://community.norton.com/t5/Norton-Internet-Security-Norton/Un-Blocking-programs/td-p/713931
http://community.norton.com/t5/Norton-Internet-Security-Norton/NEED-HELP-FAST/td-p/714429