I have a NAS device attached to my home LAN and, in one of its folders, I keep old versions of a navigation application, each being a huge EXE file (1-1.5GB). When I open this folder with my Windows 7 Pro SP1 (32-bit) Explorer, after a while the system practically stops responding. The mouse pointer disappears temporarily, I cannot close the window. Only after running Windows Task Manger BEFORE opening this folder, I could find that the problem appears to be related to AvastSvc process which, apparently, reads entire contents of all the EXE files in the folder just upon opening that folder in the Explorer. Even without any attempt to run (or even select) any of them. The system regains responsiveness only after they are fully read (scanned). The amount of increase in I/O Read Bytes column in Task Manger for AvastSvc is exactly the sum of size of all EXE files in the folder (over 9GB, takes about 15 minutes).
I am not sure why it works this way. Maybe the Explorer opens each of the EXE file and this triggers the full scan. The files are self-executable installers which decompress themselves before starting the real install process which might explain why it has to read them wholly. Although some big ZIP files, also present there, are not fully scanned.
Similar file in a local hard disk folder is also scanned upon opening the folder (so the title bar of the Explorer windows shows "Downloads (Non responding)") but it has no such severe results on the performance of the system. And also finishes faster (less files, faster disk read). This, however, contradicts the common sense - slower readout from the NAS device should make less load on the system. But, surely, this is MS Windows - the common sense does not apply
To make the things even harder to understand: My second laptop (Win XP, same, newest version of Avast Free), on the same NAS folder, does not show the above behavior. The amount of I/O read bytes in AvastSvc increases only sligthly upon opening the folder, though the Explorer seems to "touch" the EXE files also, displaying their thumbnails as icons.
On my sons's desktop (same Win7 Pro 32 bit, SP1), using Avira antivir - also no sign of extensive reading of the EXE files upod opening the folder on NAS.
There is another strange thing in which these machines differ: on both laptops, every time I right-click an EXE file in Explorer (in order to, say, display its properties or rename or whatever is in the context menu), the Explore also reads the entire file before showing the context menu (guessed from the increasing I/O Read Bytes of explorer.exe in WTM). On the desktop, it does not, the context menu appears immediately. I am really stuck.
Is there anything that can be done to avoid such problems (apart from renaming the EXE files to some "neutral" extensions, which DOES SOLVE it)?
