Scanning Google Earth - at least once a day

A window pops up several times a day that indicates that Norton Antivirus for Mac (version 11) is scanning Google Earth, regardless of whether or not Google Earth is running.  The Activity Log indicates the following:

Event Type:      Auto Disk Scan

Result:              0 Problems

Details:             /Volumes/com.GoogleEarthPlus-nhw218aYinN3NTP3UnMG3qf2yog=

 

As I look at the Activity Log I see that it also scans Google Chrome on occassion.  I downloaded that at the same time as an update with Google Earth but don't even use it.

 

The pop ups are annoying.  They don't seem to interfere with anything else but I'd like to know why they happen and if I should do anything about this.