Anthony, I've been into all these checkings. I only mentionned that touching this add verb ... line SOLVED the problem for a very short time, thus leting me into thinking that it might be related to the problem. However, having not gone much further into that way, I put it back as it was.
I have done another very interesting testing, trying to reach the website and download the files from a chinese proxy, and it worked ! So I've investingated this a little further. As i said, some people can download, others cannot, there must be some difference depending on the client :
After comparing the headers, I found this (please note the different URLs ):
WITHOUT A PROXY, A REQUEST HEADER THAT WILL FAIL THE DOWNLOAD :
GET /LinkClick.aspx?fileticket=9wfYKbaduaI%3d&tabid=183&mid=548 HTTP/1.1
THROUGHT THE PROXY, A REQUEST HEADER THAT WILL DOWNLOAD OK :
GET
http://www.dotnetnuke.fr/LinkClick.aspx?fileticket=9wfYKbaduaI%3d&tabid=183&mid=548HTTP/1.1
Also, the answer from the server is different :
IN THE CASE OF A FAILED REQUEST :
HTTP/1.1 200 OK
Cache-Control: private
Date: Mon, 25 Sep 2006 13:58:40 GMT
Content-Type: application/octet-stream
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
X-AspNet-Version: 1.1.4322
content-disposition: inline; filename=ResourcePack.Full.04.03.04.fr-FR.zip
Content-Encoding: gzip
Vary: Accept-Encoding
Transfer-Encoding: chunked
IN THE CASE OF A SUCCESSFULL REQUEST (please not the lenght of the file) :
HTTP/1.1 200 OK
Date: Mon, 25 Sep 2006 13:58:00 GMT
Content-Length: 365441
Content-Type: application/octet-stream
Cache-Control: private
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
X-AspNet-Version: 1.1.4322
content-disposition: inline; filename=ResourcePack.Full.04.03.04.fr-FR.zip
Via: 1.1 supercache3 (NetCache NetApp/6.0.4)