Use this report to see which clients generate the largest number of errors and warnings. You may want to look at the location and type of users on these clients to see why they experience more problems than others. You can then go to the System log for details
Run the Threat Analysis Scan in Symantec Help (SymHelp) and scan your system
How to run the Threat Analysis Scan in Symantec Help (SymHelp)
incase of suspicious activity still happening, then follow the steps provided in the Article below:
Using Symantec Help (SymHelp) Tool, how do we Collect the Suspicious Files and Submit the same to Symantec Security Response Team.
How To Use the Symantec Endpoint Recovery Tool with the Latest Virus Definitions
Symantec Endpoint Recovery Tool (SERT) requires a PIN to run