Normal troubleshooting goes like this.
run the latest rapid release.
reboot in safe mode
run a full scan
Note that this is not a fix for all infections.
IF you do not have a contract with Symantec for support, you can submit the files to anyone of the below sites.
http://www.threatexpert.com/submit.aspx
https://www.virustotal.com/
These sites will be able to scan the file and tell you if it is clean, though they cannot provide you a repair definition.