First of all, thanks for your fast answer.

> Anyway, you can use in 'Set Options'/'Scan rules'
> syntax 
> like:
> -*.gif*[<10]
> To exclude all gif files smaller than 10KiB

Well, it seems to b e the solution. :-)

> This might be due to two different causes:
> - The connection related to those files are
> closed suddenly without proper size information
> sent by the remote server ("streamed" files)
> - there is no way to detect the problem,
> unfortunately

Well, these files are not streamed, and when I want to 
download them individually in my regular brwoser, this last 
one know the file size (so it can give the percentage of 
the download. Wouln't be possible to HHTrack to get these 
info too, and then to compare them to the size of the final 
file ? And possibly to resume ? Netscape or IE can resume 
their download when the user chooses to stop them.