You are doing this as root, right?
One way "to do this as root" is gtksu gedit /etc/hosts
When asked, enter your
password, and press return.
Edit the file, then save it.
there is not such file called aliases
... things have changed in 9.10, and I am still on 8.04.
This is supposed to turn off ipv6, even if the aliases file is not used:
gtksu gedit /etc/modprobe.d/bad_list
enter the following
alias net-pf-10 off
Save the file.