Avast 5 automatically scans files when opening folder in windows explorer

When I open a folder in Windows Explorer the File System Shield of Avast 5 automatically starts scanning the files in that folder. Further when I move the mouse over the files in the right pane (files pane) of the Windows Explorer these files are automatically scanned. However I’m not sure this happens because of the mouse movement or because of the fact that the File System Shield is still busy with the scan caused by the opening of the folder.
Especially with large folders/files (archives) it sometimes looks like Windows Explorer is freezing, but it’s just Avast scanning.
Besides stopping the File System Shield, does anyone know if there is a possibility to switch off this automatic scanning?

Windows XP SP3
Avast Free 5.0.594
File System Shield Settings:

  • Scan documents when opening: checked
  • Scan files when writing: checked
    File System Shield Settings, possible relevant Expert settings:
  • Scan when opening: Scan documents when opening and Scan all files: checked
  • Advanced: Use transient caching: checked, Use persistent caching: unchecked

Sorry for my English, it has been better.

File System Shield Settings, possible relevant Expert settings: - Scan when opening: Scan documents when opening and Scan all files: checked

Uncheck Scan all files. I have that unchecked and experience no lag. When hovering over a file in the RH pane, the Avast icon in the system tray will rotate momentarily when Windows checks file information to show in the ‘tooltip’.

I also have persistent caching checkmarked in Advanced.

This is expected behavior - the scanning. But I am really surprised you are observing this (the lag) with avast!. avast is one of the very very few AVs left in the market which do not hog Windows Explorer even when browsing folders with large no of executable files, and still provide on-access protection. I suspect your problem is due to -

  1. improper removal of old AV, or
  2. simultaneous usage of another real-time app

If both of the above do not apply to you, then its time to take a look at your HDD controller driver.

+1 You hit the nail right on the head. Scan all files is not enabled by default. nick2000 as Gopher John said uncheck Scan all files and give it a try.

Many thanks for the replies, your suggestions helped a lot.

@Gopher John and wonderwrench
The uncheck Scan all files indeed did the trick, it stopped Avast from scanning all the files in the folder when a folder is opened.
I prefer to leave persistent caching unchecked. You never know, a clean file might be detected as infected based on new virus definitions.

@Ravi gupta
Avast 5 was installed by the Avast automatic update from Avast 4.8. To be quite on the safe site I already uninstalled Avast 5 again using the Avast uninstaller followed by runs of aswclear5.exe to remove possible remains of Avast 4 and 5. However the newly installed Avast 5 didn’t make any difference.
The real-time application that might affect Avast is the firewall of Online Armor. I tried Private Firewall but that too didn’t make any difference.
I don’t have any idea how to check the working of the HDD controller driver, but at the moment all seems to work perfectly.

Again many thanks guys for your help.

The persistent cache is a little smarter than that and not all and sundry files can populate it, check the avast file relating to it. The key is the word Verified.

Edited typo

I had started a similar thread regarding persistent cache and if it could get “poisoned” some time ago. Devs assured me it can’t happen, so relax, enable it and have fun using your PC