is it happening on one client or all the clients
If one client then
go to
c:\Documents and Settings\All Users\Application Data\Symantec\Symantec Endpoint Protection\Quarantine
and delete all the files then from SEPM -antivirus and Antispyware Policy -Quarantine --Purge options
SEP the size of Quarantine to 50 MB
after deleting the files you can do that from the client also
Open SEP clients- Change Settings- Viw Quarantine _purge Options there you can set the size to 50 MB