> But some files are downloaded
> as a html site without retrieving the original time
> stamp. What's this kind of technique??? Any chance
> to retrieve the timestamp of this files too?
The timestamp comes from the server.  
Any server generated html (cgi, jsp, php, etc) has the current time not the
script timestamp.  
They also change if the owner restored files from a backup but didn't keep the
timestamp (copy vs xcopy)