Extra 266 GB scanned since update?

[bluto32]

I have Windows 7 64bit Ultimate, and updated Avast to the latest version last night.

I did a full system scan; nothing found. But it took 60 minutes rather than the usual 40 minutes it has done for the last few years. The previous scan I did was two weeks ago before going away on holiday. I compared the scan histories of these two scans:

4th July
No threat found
40 minutes
372 GB tested
35803 folders
362895 files

24th July
No threat found
60 minutes
638 GB tested (up by 266 GB!!!)
36554 folders (up by 751)
494756 files (up by 131,861!)


That's quite a difference, and I'm puzzled as to what/where all this extra data is. Between the two scans, I haven't used my PC much due to being away. This is what was done in between the scans:

• Windows did 30 updates (quite a lot in one go, but then I was away for 2 weeks)
• Updated 2 small programs (MP3tag and Exact Audio Copy)
• Watched one episode of "Breaking Bad" online which had failed to record on my PVR

The last one was foolish, I know and slightly worrying. While trying to find a link which worked, IE was hijacked temporarily with a popup which demanded payment to receive some malware-removal software. I killed it in Task Manager; all fine afterwards and no obvious symptoms of any malware. MalwareBytes didn't find anything either. Could an infection cause so many files to be created?

Thanks for any suggestions as to where these extra files/folders have suddenly come from.

Bluto

[mchain]

See:  https://forum.avast.com/index.php?topic=173874.msg1234834#msg1234834

Pls read to see if this applies to you.

[bluto32]

Thanks for replying - much appreciated.

I read the thread and remembered that I had reset the preferences just after updating Avast. I don't think I have a way of seeing what they were before with the previous version. Just in case, I did another "reset" in Avast and then another full system scan. Still taking about an hour and scanning 638 GB.

The preferences after a reset are set as follows:

Scan Parameters
"Scan all files"   is not checked

Sensitivity:
"use code emulation"   and   "scan for PUPs"   are checked;
"test whole files"   and   "follow links during scan"   are not checked.

Packers: only these 5 are checked:

• self-extracting DOS
• self-extracting Win32
• Droppers
• Installer archive
• NTFS stream

Are there any other preferences I should be looking at?

Also, here are the sizes of my two hard drives when right-clicking them and viewing properties:
C: 489 GB
J: 111 GB (external hard disk)

Note these add up to only 600 GB, and Avast says it has scanned 638 GB!

However, if I view all file types and hidden files in Explorer, and then select ALL files in the root directory of C, the properties for these files only gives 227 GB, not 489. I'm guessing the rest is system-restore info. I tried deleting a few restore points in CCleaner, but it didn't change the amount of stuff Avast is scanning: still 638 GB.

Bluto