Check this KB -
Removing security risks with Symantec AntiVirus 10.x or Client Security 3.x
http://www.symantec.com/business/support/index?page=content&id=TECH101239&actp=search&viewlocale=en_US&searchid=1321887407713
If you are using Symantec System Center, this KB may be helpful -
Cannot delete quarantined files from individual clients in Symantec System Center
http://www.symantec.com/business/support/index?page=content&id=TECH101896&actp=search&viewlocale=en_US&searchid=1321887525722
Let us know if this resolved your issue.
Best,
Thomas