Try to look in the quarantine folder on the client. if there is something inthere delete it.
And on your sav server there is a checkmark to scan when new def is installed under quantine options, you could choose to deselect this. This will stop those malware warnings when something is already in quantine
After you update virus definitions, Symantec AntiVirus Corporate Edition 10.1 runs a Defwatch Quick Scan. Symantec AntiVirus quarantines security risks for which you created an exception during this Quick Scan, unless you use global security risk exclusions. To fix this problem, disable the Defwatch Quick Scan.
To disable the Defwatch Quick Scan on managed clients
Start Symantec System Center.
Unlock the server group.
Right-click a server group, a client group, or a server, and then click All Tasks > Symantec AntiVirus > Client Administrator Only Options.
On the Scans tab, under Triggered Scans, uncheck Run a Quick Scan when new definitions arrive.
Click OK.
http://service1.symantec.com/SUPPORT/ent-security.nsf/0/9af3a5f8ba65fa3d8825713b00653045?OpenDocument&seg=hm