Unsolicited Silent Mode Interrupts Custom Scan

Last night I put my system into a custom scan because it had not been scanned in over two weeks due to a hospital admission and no access to a home PC. This morning I put my monitor on and saw a message saying that the scan had been interrupted due to silent mode. I tried the solution shown in a previous question about this same situation and it did not apply to my problem.

 

Windows 7 Home Premium 64-bit running Norton Security Suite 21.5.0.19 provided by Comcast

No overnight tasks running, scan is scheduled for 2am on Sundays, but I ran it at 2:45am 

Silent Mode is set to run on detection of Firefox, Chrome, SimCity 4, and Zelda Classic. However none of these programs ran, and all other detection settings are OFF.