Hello and welcome Alex.
There are a few issues with free AVG and Windows 8.1. Please see a few articles frim AVG on these problems below -
AVG system requirements and supported operating systems
Reinstall AVG after upgrade to Windows 8 or 8.1
AVG PC TuneUp compatibility with Windows 8.1
Please also run this Temp File cleaner, as the detection may have been caught, but not thrown out yet.
Please download Temp File Cleaner by Old Timer
1.Download TFC from the download link above and save the file on your desktop.
2.Close ALL running applications as TFC will terminate them before attempting to clean up the temporary files.
3.Double-click on the TFC icon.
4.When the program opens, click on the Start button. TFC will terminate the Explorer process and all running applications and then begin the process of cleaning out all of your temp folders.
5.When done, press OK > Exit, and Reboot your computer and finish the cleanup..............
- Please download Malwarebytes Anti-Malware andf ollow the simple directions to install the program to desktop
- Right click and choose "Run as administrator" to open Malwarebytes Anti-Malware and from the Dashboard please Check for Updates by clicking the Update Now... link
- Open up Malwarebytes > Settings > Detection and Protection > Enable Scan for rootkit and Under Non Malware Protection set both PUP and PUM to Treat detections as malware.
- Click on the SCAN button and run a Threat Scan with Malwarebytes Anti-Malware by clicking the Scan Now>> button.
- If you find malware and tick it to remove it, you may be asked th re-boot the computer to finish cleaning.
- Once completed please click on the History > Application Logs and find your scan log and open it and then click on the "copy to clipboard" button and post back the results on your next reply.
If you wish to Uninstall and Reinstall your free version please visit This Malwarebytes Page.
Let us know the results -
If you have the time >> Run ESET Online Scanner.
NOTE:Sometimes if ESET finds no infections it will not create a log.