btw, sorry bram if i didn't answer to your questions, but i was a little busy in these days...
whatever, you r great!
the problem was related to a buggy driver in a slightly older version of Ubuntu.
Jordi, our Great Sysadmin upgraded freesound to the latest version of ubuntu, installed newer drivers in the virtual machine and ... done!
Aah, I haven't returned to this post in a while. I forgot I had made it, but now everything is running smoothly with no slow download time. Thank you very much Bram.
Thanks guys for the help...