Discussed fairly regularly, here.
My preferred workaround is to place a virus test file (this is an industry-produced "fake" virus signature, downloadable from
Eicar, near the beginning of the scanning area. (Check your scanned items at the beginning of the scan to see where this should be.)
You'll have to disable the webshield briefly to download the file.
Once the file is placed, carry out a scan. Wait until the file is alerted, choose "no action", and tick the box "do not show me this again next time".
At the end of the scan, you can view the report and decide appropriate actions.
Search "scheduled scanning" or "automatic action" in the forum.