Comment 6 for bug 106958

Well, my colleague may have found the problem.
It seems that it is a kernel configuration since 2.6.17 that is in cause.
On my machine, and those of my colleague, setting net.ipv4.tcp_rmem works fine. I've not yet tested on other machines that had similar problem ...

To set this configuration, run :
sudo sysctl -w net.ipv4.tcp_window_scaling=0
Or append "net.ipv4.tcp_window_scaling=0" in /etc/sysctl.conf

It seems (on french forums) that this configuration coulod affect local wide transfers, in this case, configuration of kernel < 2.6.17 is "net.ipv4.tcp_rmem=4096 87380 174760".

French source :
http://doc.ubuntu-fr.org/feisty_internet_problemes
http://forum.ubuntu-fr.org/viewtopic.php?pid=831529#p831529