From the image, that looks like it is likely to be a virus signature file, avscan.dll so it would appear that this is unencrypted otherwise avast wouldn't be able to scan it. avast can't extract part of the avscan.dll 'archive' without corrupting the dll I would think so the operation is unsupported and failed.
Do you know what this avscan.dll came with, in your computer stuff\...(sub folder not shown in the image)\ if it is an installed AV I would suggest that you uninstall or remove it. It could be windows onecare or antivir
Component Name: avscan.dll
Description of avscan.dll
This is a component of Microsoft Windows OneCare Live. Windows Live OneCare, from Microsoft, is a suite designed to integrate anti-spyware, anti-virus, firewall and other security functions.
OR
Component Name: avscan.dll
Description of avscan.dll
This is a component of Avira AntiVir Personal. AntiVir PersonalEdition is a security software that can detect and remove viruses, unwanted programs, and other malware types. Scans can be configured and employ both database and behavior-based methods in detecting the presence of a virus on a computer. It can schedule single or recurring tasks such as updates and scans.
Or perhaps something different but using this file name.
I would suggest cleaning up the system information information folder and recover some HDD space.
Create Clean Restore Point - Clear old Restore Points.
Create a clean System Restore point:
1. Click Start, All Programs, Accessories, System tools, System Restore.
2. In the pop-up that appears fill in the radio button to Create a Restore Point
3. Click NEXT
4. Enter a useful name that you will remember if you need to find this again (Clean Restore Point)
5. Click CREATE
You now have a clean restore point, you should clear the old ones:
1. Click Start, All Programs, Accessories, System tools, Disk Clean Up
2. Click OK on the C: drive
3. Click the More Options tab
4. In the System Restore section click the Clean Up button
