Hello,Had that very same problem when installing Ubuntu 12.04 a while back and with Trisquel 6.0 recently. During installation (at 'please wait') the installation stalled and refused to continue until I simply disconnected from the internet, waited a bit, and it continued to install like magic!
It'll probably be easier from the beginning to not connect to the internet at all though.
But as with Trisquel 5.5 it is the same solution for Trisquel 6.0.
