No, files Avast detected are probably only password protected, so Avast could not access them, so it reported this. Do not touch them.
To hide files, look here:
http://www.howtogeek.com/194671/how-to-hide-files-and-folders-on-every-operating-system/
https://sites.google.com/site/cannedfixes/farbar-recovery-scan-tool/FRST.gif
Scan with Farbar Recovery Scan Tool
Please re-run Farbar Recovery Scan Tool to give me a fresh look at your system.
[*]Right-click on
https://sites.google.com/site/cannedfixes/farbar-recovery-scan-tool/FRST.gif
icon and select
https://sites.google.com/site/cannedfixes/home/hosted-images-tools/RunAsAdmin.jpg
Run as Administrator to start the tool.
(XP users click run after receipt of Windows Security Warning - Open File).
[*]Make sure that Addition option is checked.
[*]Press Scan button and wait.
[*]The tool will produce two logfiles on your desktop: FRST.txt and Addition.txt.
Please include their content into your next reply.