Here are a few KB's to chew on.
The Home, Monitors, and Reports tabs in the Endpoint Protection Manager aren't loading completely - Images and graphs are missing.
http://www.symantec.com/business/support/index?page=content&id=TECH103853&locale=en_US
Symantec Endpoint Protection Manager: Home, Monitors, and Reports tabs do not display graphics
http://www.symantec.com/business/support/index?page=content&id=TECH105141&locale=en_US
Home, Monitors, and Reports tabs are blank in the Symantec Endpoint Protection Manager Remote Console
http://www.symantec.com/business/support/index?page=content&id=TECH103832&locale=en_US
Home, Monitors, and Reports tabs are blank in the Symantec Endpoint Protection Manager.
http://www.symantec.com/business/support/index?page=content&id=TECH103816&actp=search&viewlocale=en_US&searchid=1291828872045
Symantec Endpoint Protection Manager: Home, Reports, and Monitor pages are blank and no error messages are displayed
http://www.symantec.com/business/support/index?page=content&id=TECH103156&actp=search&viewlocale=en_US&searchid=1291828872045
Reporting Troubleshooting in Symantec Endpoint Protection (SEP) 11.x
http://www.symantec.com/business/support/index?page=content&id=TECH105617&locale=en_US