Did you run a full SEP scan with latest defs?
If so and it found nothing, try the threat analysis scan:
How to run the Threat Analysis Scan in Symantec Help (SymHelp)
http://www.symantec.com/docs/TECH215519
If neither of the above work, download AdwCleaner and Junk Removal Tool and run them.
Some additional reading:
Security Response recommendations for Symantec Endpoint Protection 12.1 settings
http://www.symantec.com/docs/TECH173752
Is your system infected? Symantec tools to help clear an infection
https://www-secure.symantec.com/connect/forums/your-system-infected-symantec-tools-help-clear-infection
Eliminating viruses and security risks
http://www.symantec.com/docs/HOWTO27280
Security Best Practice Recommendations
http://www.symantec.com/docs/TECH91705