Having two active AV scanners will not help- it will only cause conflicts and instability.
Have you tried a boot time scan with avast!? Right click the scanner screen, select ‘schedule a boot time scan’ and reboot when requested.
Try a scan with AVG in Safe Mode.
(There’s no guarantee that either AV will work properly with another present.)
Try a few online scans in Safe Mode with Networking.
F-Secure
BitDefender
Panda
Trend Micro Housecall