Hi, since you are using McAfee Internet Security, I think maybe you could add GetSusp to your collection of On-demand scanners.
The default level of the sensitivity of Artemis are set to 3 in both On-Access detection and On-Demand detection of McAfee for-home products, while the maximum level should be at least 4.
By contrast, according to the McAfee community, GetSusp is always running with the highest level of sensitivity. So it can detect something that may be missed by McAfee IS.
Although it cannot isolate the threats, with this tool you can easily submit the suspicious files to McAfee.
When I used the products of McAfee, I found this tool is quite useful.
You can find it here:
GetSusp | McAfee Free Tools