Slowdown scanning exe files

[AlphaUMi]

Hi!

I have Win XP SP3 x86 updated, 2 GB ram. Since the last avast's update to version 5.1 (now I'm running 5.1.889), I keep noticing an instant slowdown when avast! is scanning a folder containing an exe file (most of the times an installer package). The window is blocked, the system tray is blocked, and I have to wait until the end of the scan. If the exe is large (I mean +100 MB), it can take up to 1 minute or so to complete the scan. And if I temporary disable the various shields, this issue doesn't occur. Is this a known issue, or is it only related to me? And what could I do, please, to solve this problem?

Thanks in advance...

[Lisandro]

Well, did you change the File Shield settings?
You can add the file to the Exclusion lists (on File Shield settings and on main settings). Oh, I suppose it's a clean file.

[AlphaUMi]

Uh... I haven't explained the issue well, sorry. That problem occurs with any exe file, not with one in particular. And the sensitivity of the scanner is set to "Normal"...

[AlphaUMi]

Well, no one has encountered the same problem? 

[igor]

What scan exactly are we talking about?  An on-demand scan you started manually from the GUI, or resident shields? I suppose the later...
In that case, it shouldn't really scan "a folder" - so what triggers the scan? You entering the folder in some file manager? Which one - Explorer?

[AlphaUMi]

Yes, I browse normally through my folders, and when I open a folder with an executable inside (any folder) the resident shield start analysing (I notice the icon rounding), but suddenly it freezes for a while (and the folder too, I can't move it nor select a file), until the avast icon ends his round and all is normal again.

If I temporary disable the protection shields this doesn't happens, so it must be avast. What could it be?