I tried to connect directly to the servers with explorer directly to this line :
http://download1.avast.com/iavs4x
and so with each server in my servers.def and the answer is that The requested URL /iavs4x/ was not found on this server. Is it normal ?
I’m trying to update my avs database since february 16th 2006 and it doesn’t work.
Avast 4 home
Win2k pro.
Right click the avast icon and select, Updating, iAVS Update and avast does the connections, it selects which server to used based on server load. The server.def is not a user file but one that the avast update process updates and uses.
So when used directly it won’t work as the information on what to update from what version of iAVS you have isn’t there. Updates are designed to be done either automatically or manually as I described above, but always through the avast update process.
You can download the complete VPS file, used for updating systems not connected to the internet and execute that file off-line on the system required.
avast! VPS Update - Manual Download
Welcome to the forums, kabeda. 
Let us know if this solved your problem.
Please come back often, learn more, and maybe help others.
I already tried with this file “vpsupd.exe” and I had this error (the file attached).
You’re using 4.6.731 and the last version is 4.6.763.
Can you download the full setup file and update your system?
If it does not work, just uninstall the previous version, boot, install the new one 
It’s normal, because virtual directory listings are disabled on our servers.
Updates from all servers are working normally, you may just need to check your internet/firewall settings.
What does this mean for non-technical users… Is it that we can’t ‘see’ the contents of the directory servers (like we can’t use the old command ‘dir’)?
Hopefully, this link will help and not be too technical …
http://en.wikipedia.org/wiki/Virtual_directory
CharleyO: it’s not that ‘Virtual Directory’
Tech: yeah, you’re right
In Apache’s (our webserver) terminology that means if the directory does not have any index file (index.html, index.htm, index.php or so), it by default tries to display the contents of a directory in human readable form with links and icons and such.
We’ve disabled such feature (because of multiple reasons), that’s why you can point your browser to existing directory, but still get message about non-existing directory 8) It’s possible to get the file from the directory, though.
Sorry about posting the wrong type of Virtual Directory, kubecj. 