Hi,
Blocked IP address is from internal network or it's unknown IP ?
If it's internal IP address, you can exclude IP address through IPS policy.
It is's unknown IP address, check for System vulnerability.
It is recommended to install all the Symantec features AV / PTP/ NTP with latest definitions.Always make sure that your computers are receiving definitions regularly.
You windows machines should have all the latest windows updates /Patches.